Laravel connect to SFTP

I have "league/flysystem-sftp": "~1.0", and I try to connect to the server, the data are correct (if I try some wrong data I get an error), but I don't get any relevant info, for example, if a file exists, or how to access it.

$exists = Storage::disk('sftp')->getDriver()->getAdapter();
dd($exists);

League\Flysystem\Sftp\SftpAdapter {#2189 ▼
  #connection: null
  #port: 22
  #hostFingerprint: null
  #privateKey: ""
  #useAgent: false
  #usePingForConnectivityCheck: false
  -agent: null
  #configurable: array:16 [▶]
  #statMap: array:2 [▶]
  #directoryPerm: 484
  -passphrase: null
  #host: "MY HOST IP"
  #ssl: false
  #timeout: 90
  #passive: true
  #separator: "/"
  #root: null
  #permPublic: 484
  #permPrivate: 448
  #systemType: null
  #safeStorage: League\Flysystem\SafeStorage {#2184 ▶}
  #enableTimestampsOnUnixListings: false
  #pathPrefix: null
  #pathSeparator: "/"
}

If I try the same thing for 'local' I get #pathPrefix: "/home/vagrant/lmsx/storage/app/"

filesystems.php

'sftp' => [
    'driver' => 'sftp',
    'host' => env('SFTP_HOST'),
    'username' => env('SFTP_USERNAME'),
    'password' => env('SFTP_PASSWORD'),
    'privateKey' => env('SFTP_PRIVATE_KEY'),
    'port' => 22,
],