How to push a video format file to the Google Drive from an Android app?

I'm trying to make my Android app to upload a Video format file to my Google Drive account. The whole code:

import android.Manifest;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.media.MediaMetadataRetriever;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.fragment.app.Fragment;

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.ExponentialBackOff;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.FileList;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URLConnection;
import java.security.GeneralSecurityException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import static net.fortuna.ical4j.util.ResourceLoader.getResourceAsStream;

public class ManagerUploadFragment extends Fragment {
    private final static int APP_PERMISSION_REQUEST = 100;
    private final static int ACTIVITY_CHOOSE_FILE = 1;

    private static final String APPLICATION_NAME = "Google Drive API Java Quickstart";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKENS_DIRECTORY_PATH = "tokens";


    private static final List<String> SCOPES = Collections.singletonList(DriveScopes.DRIVE_METADATA_READONLY);
    private static final String CREDENTIALS_FILE_PATH = "/credentials.json";


    private View fragmentView;

    private Button uploadButton;

    private Drive driveService;

    // Required empty public constructor for fragments
    public ManagerUploadFragment() {}

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        fragmentView = inflater.inflate(R.layout.fragment_manager_upload, container, false);

        uploadButton = (Button) fragmentView.findViewById(R.id.upload_view_browse_button);

        // Set upload button
        uploadButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                uploadImage();
            }
        });

        // Connect to drive
        try {
            driveService = createService();
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return fragmentView;
    }


    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == APP_PERMISSION_REQUEST) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                for (int grantResult : grantResults) {
                    if (grantResult != PackageManager.PERMISSION_GRANTED) {
                        Toast.makeText(getActivity(), R.string.enable_required_permissions, Toast.LENGTH_LONG).show();
                        return; // Permissions were not granted
                    }
                }
            }
        }
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == AppCompatActivity.RESULT_OK) {
            if (requestCode == ACTIVITY_CHOOSE_FILE && getActivity() != null) {
                Uri uri = data.getData();
                System.out.println("URI " + uri.toString());
                if (!(isVideoFile(uri))) {
                    Toast.makeText(getActivity(), "File is not in a valid video format", Toast.LENGTH_LONG).show();
                    return;
                }
                if (getFileSizeInMB(uri.getPath()) > 1) {
                    Toast.makeText(getActivity(), "File size is bigger than 20MB", Toast.LENGTH_LONG).show();
                    return;
                }
            }
        }
    }

    private static long getFileSizeInMB(final String file_path) {
        final File file = new File(file_path);
        long sizeInBytes = file.length();
        return sizeInBytes / (1024 * 1024);
    }

    private boolean isVideoFile(Uri uri) {
        ContentResolver cR = getContext().getContentResolver();
        String type = cR.getType(uri);
        return type != null && (type.equals("video/mp4") || type.equals("video/avi"));
    }

    private void uploadImage() {
        if (getActivity() != null) {
            final int writeStoragePermission = ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE);
            final int readStoragePermission = ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.READ_EXTERNAL_STORAGE);
            if (writeStoragePermission != PackageManager.PERMISSION_GRANTED || readStoragePermission != PackageManager.PERMISSION_GRANTED) {
                final String[] permissions = new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE};
                ActivityCompat.requestPermissions(getActivity(), permissions, APP_PERMISSION_REQUEST);
                return;
            }

            Intent chooseFile;
            Intent intent;
            chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
            chooseFile.addCategory(Intent.CATEGORY_OPENABLE);
            chooseFile.setType("*/*");
            intent = Intent.createChooser(chooseFile, "Choose a file");
            startActivityForResult(intent, ACTIVITY_CHOOSE_FILE);
        }
    }

    private Drive createService() throws GeneralSecurityException, IOException {
        final NetHttpTransport HTTP_TRANSPORT = new com.google.api.client.http.javanet.NetHttpTransport();
        Drive mService = new Drive.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(getContext(), HTTP_TRANSPORT))
                .setApplicationName(APPLICATION_NAME)
                .build();

        // Print the names and IDs for up to 10 files.
        FileList result = mService.files().list()
                .setPageSize(10)
                .setFields("nextPageToken, files(id, name)")
                .execute();
        List<com.google.api.services.drive.model.File> files = result.getFiles();
        if (files == null || files.isEmpty()) {
            System.out.println("No files found.");
        } else {
            System.out.println("Files:");
            for (com.google.api.services.drive.model.File file : files) {
                System.out.printf("%s (%s)\n", file.getName(), file.getId());
            }
        }
        return mService;
    }

    private static Credential getCredentials(final Context context, final NetHttpTransport HTTP_TRANSPORT) throws IOException {
        // Load client secrets.
        InputStream in = context.getClass().getResourceAsStream(CREDENTIALS_FILE_PATH);
        if (in == null) {
            throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
        }
        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

        // Build flow and trigger user authorization request.
        GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
                HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
                .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
                .setAccessType("offline")
                .build();
        LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
        return new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
    }
}

In order to upload the video to the Dirve, I need to connect to the Drive first. I followed the steps on how to create to use the API (docs). Then I followed this example, which should show how to connect to the Google Drive and list the content.

But, before even pressing the "upload" button, I get an error to connect to the Google Drive:

java.io.IOException: unable to create directory: /tokens

On line:

GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
                HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
                .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
                .setAccessType("offline")
                .build();

Please correct me if I'm wrong, but as I understand, it tries to create the token directory locally and not in the remote - but why does it need it? I just want to be able to push the video I got from the user to the Drive. How can I connect to the Google Drive and push the video to the Drive (if you will take a look into a code, I have the uri of the file, that should be pushed to the Drive).