Right now, the vibe share feature is only available when using Spotify Premium playback.
Due to Apple Music’s DRM restrictions at this time, we cannot apply Vibes on streaming Apple Music or on offline downloads from the Apple Music streaming service. We can only apple Vibes to music you’ve directly downloaded or imported to your iPhone/iPad. This includes music you’ve purchased as direct downloads from iTunes/Apple Music, or music you’ve directly added to your device from your computer. To see more tracks in Local Music, you can either add tracks locally to your device by syncing with your computer, or by opening Apple Music on your device and downloading the tracks you’ve already purchased. Once downloaded, they will appear in the Local Music tab.
Audible Reality currently supports playback from Spotify Premium (but not with Spotify free). You can also play music from your phone that has been purchased AND downloaded through iTunes/Apple Music. More services coming very soon!