PS: Perhaps that previous linked article is too old to be useful.
Wondering if it would help to restart your son's iPhone (turn off , turn back on)
That can often help correct things if an app isn't working as expected.
On iPhone with iOS16: See what your friends are listening to – Apple Support
says:
"Create a profile
When you first open Music, you’re asked to set up a profile and start following friends.
If you skipped this step, you can set up a profile at any time.
Tap Listen Now,
then tap the grey oval "person" icon
Tap Start Sharing with Friends.
Friends can now follow you."
Similar to above for iPad
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On Mac OS Ventura: How to: Create an Apple Music profile on Mac – Apple Support
Share songs from a shared media library in Music on Mac – Apple Support
Share Apple Music with Family Sharing on Mac – Apple Support
If you use Apple Music on the web:
Set or change parental controls in Apple Music on the web – Apple Support