Music Transfer

I recently bought a new iMac, running Monterey. I have tried to copy over my old iTunes library/playlists from my old iMac, following the instructions I've found on here, however, it is not working right. SOME of the music carried over, but not all of it, and none of my playlists carried over. I have a lot of music/playlists that I have collected over the years - much of which were my own old CDs, etc. I am a dance teacher, and need to access my playlists. Is there any way to just copy what is currently on my iPad to the Music app on the Mac? Or is there another way to do this without losing all my music?? I've never had a problem transferring content when upgrading my devices before and I'm not sure why this isn't working. I'm getting very frustrated. Any ideas???