i have a mac. I am repeatedly being asked to authorize my device

See the following from Authorize or deauthorize your computer for iTunes Store purchases - Apple Support

How to authorize or deauthorize your Mac

1. Open the Apple Music app or Apple TV app. In the menu bar, choose Account and make sure that you're signed in with your Apple ID.
2. Choose Account > Authorizations, then choose Authorize This Computer or Deauthorize This Computer.
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5. Sign in with your Apple ID and password. Forgot your Apple ID?
6. Click Authorize or Deauthorize.

Repeated requests to authorize an already authorized computer for store downloads typically indicates you have corrupt or incomplete copies. Backup and then delete the tracks that won't play from your library without hiding from your purchase history. Redownload using the cloud links that should remain, or close iTunes and reopen if they don't show up straight away. While downloading click the activity widget and turn off the option that allows for simultaneous downloads.

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