Access browser tabs, Access your data for all websites.
No reason for this, if it only needs to look at open.spotify.com. Use the other addon that doesn't do this.

Doesn't work, just focuses the spotify app without going to the song/link in the app. Unusable in current state, but great idea for an app.

Opens the app but doesn't open the song

Doesn't work. When I click a link, it just opens the extension settings in firefox. :/

It just doesn't work for me.