concerns about upgrading from iTunes to Apple Music

Hello all, I have an old iMac that is still running IOS Mojave because I am afraid to lose my iTunes collection. I have an extensive collection of music I already own. Most are albums (not playlists) and a good portion is of my own music or my brothers' music. I have been afraid to upgrade my Mac because I don't know if all of my music will transfer to Apple Music correctly. I want to be able to keep listening to music in albums, not individual songs. I also don't see why I would need to pay for an Apple Music 'subscription' to continue listening to my own music that I have already bought. Any thoughts on this dilemma? Thanks much... Carol