Howdy joeycfc8,
If you're not able to play music via Apple Music while disconnected from the internet, it may be due to not having made said music available offline. The steps outlined below detail how to make music available offline, so that it can be listened to at any time.
You can download songs, albums, or playlists to your device so that you can listen to them when you're not connected to the Internet.* You must download songs, albums, or playlists on each device that you want to use for offline listening.
*You can download music on up to 10 devices. These songs are accessible only during your Apple Music membership.
- In the Music app, find the item that you want to download.
- Tap the More Options icon
to the right of the song, album, or playlist name.
- Tap the Download icon
to the right of the item's artwork. If you see a
instead of the download icon, the item isn't in your iCloud Music Library. Tap the
to add the item to My Music, then tap the download icon to download the item to your device.
Songs and albums appear under My Music > Library. Playlists appear under My Music > Playlists.
Add music from the Apple Music catalog to your library on your iPhone, iPad, iPod touch, Mac, or PC
https://support.apple.com/en-us/HT204839
All my best.