Apple Watch 4
I just received an Apple Watch series 4 with GPS and Cell service. I can't get Spotify to work on the phone as a stand alone from my iPhone. I'm wondering if this is something with the Spotify ap?
Apple Watch Series 4, watchOS 5
To the best of my knowledge Only Apple Music can stream to the Apple Watch.
I think Spotify and Pandora have paid options that allow downloading music and storing it on the Apple Watch that you can then play without needing a network connection. You will have to check their websites and the different paid plans they offer to be sure.