your computer is not authorized... must authorize from account menu to download previous purchases...

Open the Music app and use the Account menu there.

For more information about authorizing iTunes purchases on a Mac, 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.