ITUNES LIBRARY MISSING CONTENT

Hi,

I have recently purchased new 27 inch iMac running Monterey 12.0.1. I went into the new Music app and found my downloaded library was missing quite a few albums.

I checked I Tunes on my old iMac (21 inch running Sierra 10.12.6) and they are all there.

This appears to be a common problem with "music" vs "iTunes".

How do I get the missing albums onto my new iMac?

Rob