Hi Markden1934,
Thanks for contacting Apple Support Communities!
We understand that you're seeing an alert when you attempt to stream music via the Music app.
Do you experience the same behavior after you restart your iPhone? If you need help to restart, this article will guide you: Restart your iPhone - Apple Support
"How to restart your iPhone X, 11, 12, 13, or later
- Press and hold either volume button and the side button until the power-off slider appears.
2. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo."
If you go to Settings > Cellular > Music, do you have Music enabled here?
Do you experience the same behavior while connected to any Wi-Fi network?
We look forward to your reply.
Cheers!