How do I authenticate Spotipy with a Flask webserver?

I'm trying to make a dashboard that controls Spotify playback with Flask. I've been trying to use Spotipy to achieve this, but I am confused on how to authenticate a user token through a Flask server.

This is my code currently:

from flask import Flask, jsonify, request, render_template
import os
import spotipy
from spotipy.oauth2 import SpotifyOAuth

sp = spotipy.Spotify(auth_manager=SpotifyOAuth(client_id="id",
                                               client_secret="secret",
                                               redirect_uri="http://localhost:5000",
                                               scope="user-read-playback-state,user-modify-playback-state,user-read-currently-playing,app-remote-control"))

app = Flask(__name__)
    
@app.route("/")
def index():
    return render_template("index.html")

@app.route('/pause')
def pause():
    sp.pause_playback()

if __name__ == "__main__":
    app.run(debug=True)