To use the application:

Username: spotifytestuser22@gmail.com

Password: spotifyuser

How to use: Login using this Spotify Test User and open in your device the spotify web application and start a music.

(That's necessary because Spotify API doesn't recognize this application as a device)

After that, you can open the playlists and see the songs list, but the Spotify API requires a Premium Account to listen the songs.