Make the following checks:
Check that you have an active Internet connection.
Make sure you are in the correct login screen:
o If you created your Facebook account, click on START SESSION WITH FACEBOOK.
o If you created your account with a username and password, enter them and click on START SESSION.
Note: if you use a username, be sure to enter the username, not your email address.
If you are a "Free" user, remember that abroad you can only use Spotify for 14 days at a time. After them, you must reconnect to Spotify in the country in which you registered, or change your country settings.
Close the app and open it again.
Restart the device on which you are using Spotify.