WP Spotify – how do I make this plug-in work?

I want to add a spotify playlist to my widgets, so I downloaded the WP-Spotify plug-in. I can see the option to add the playlist to my widget, but it doesn’t pick up the songs from my Spotify account.

I’m assuming it’s because I haven’t entered my username and password. And I would, but I can’t find where I’m supposed to put it and there’s no helpful documentation that comes with the plug-in. Any help would be gratefully received.

Thanks,

Kate