one mac shared with other people, ID Apple associated to iTunes purchases

McViga,

It is as you say, you should be able to utilize separate user accounts as long as they have their own Apple IDs for purchases. So, let's look into some other causes to this by first starting the Mac in safe mode and trying to play music in the same way. You may have to check more than one account to be sure and reauthorize while in safe mode: Start up your Mac in safe mode - Apple Support

If it is working in safe mode, restart the Mac back to normal and try again.

Also, if you get any error messages, let us know what those are.

Take care.

Hi McViga,

What happens when users try to play music while signed into their accounts?

Also, which user is able to play music? Is it only the "admin" or "standard" account?

Check out the guidance below which can help isolate and resolve this:

"If you can’t play a song

• If you can’t play a song purchased from the iTunes Store: You may have exceeded the number of computers on which you can play your purchases.
• If the song isn’t an iTunes Plus version, you can play it on up to five authorized computers. After you authorize five computers, you can’t play the songs on a sixth computer until you deauthorize one of the five authorized computers. (For instructions on deauthorizing a computer, see Authorize a Mac to play iTunes Store purchases.)
• If the song is available as an iTunes Plus download, you can upgrade the song at the iTunes Store. See Usage rights for iTunes Store purchases.
• If you’re listening to a shared library or playlist: Music skips iTunes Store purchases if your computer hasn’t been authorized to play them. To listen to a purchased song in a shared library or playlist, double-click the song. If your computer isn’t authorized to play songs purchased by the person who is sharing the song, to hear it you’ll need to enter that person’s Apple ID and password. See Share songs from a shared library in Music.
• If you’re trying to play an AAC file that was not created using Music or downloaded from the iTunes Store: Songs you download from the iTunes Store or import into your library using the AAC encoder are encoded using the MPEG-4 AAC format. Songs in this format play in Music and on your iPhone, iPad, and iPod. Other AAC files that you find on the internet or elsewhere won’t play in Music. See Choose import settings.
• If you’re trying to play a song on a CD that you burned using Music: You can’t play DVDs burned using Music on most consumer DVD players. So make sure the playback equipment you’re using is appropriate for the disc’s format. For example, if you burned a CD-RW disc, you can play it only on your computer and some newer CD players. If you burned an MP3 disc, it should work in your computer and on special MP3 CD players but not on standard consumer audio CD players. See Intro to burning CDs and DVDs.
• If you’re listening to a playlist that includes a song preview: The playlist stops after the song preview. Double-click the next song in the playlist to resume playing the rest of the playlist. A song preview in your library or a playlist has a button next to it showing the price.

If songs are missing or dimmed, see the Apple Support article If songs are missing from your music library after you turn on Sync Library.

"

If you have problems playing music on Mac - Apple Support

Cheers.