Forgive my stupidness but which one of the 2 Spotify plugins should be activated? Searched but can’t find any clear info about the differences.
It depends what you want to achieve.
The Spotify plugin is similar to using the official Spotify app, in that you can see playlists, do searches etc. within Volumio’s UI.
Spotify Connect is “simply” an end point (audio out) for your official Spotify app … you can select it from within the app just like a bluetooth speaker.