Catalog during update to COP 20, need help!

I had COP 18 or 19 (prob 19) on an Intel iMac. I think it was running Catalina. The images are on an external.

I bought COP 20 and attempted an update but, it was a mess. I gave up. Then pandemic just had me set all of that stuff aside. But in the mean time, I did get a Mac mini M1. I did a clean OS install versus a migration so, no COP came over. That mini is now running Monterey. Now I am back and so I installed (migrated?) the COP 20 program on the M1 mini. But the catalog did not come over. So I thought I found it and added it but, during the add, I could tell, something was not right. It kept rejecting my long, long ago (should not be an issue since I have had other COP ones a few times since then and was fully converted over) Apple Aperture stuff.

It was just not right. Sure enough, the catalog is as total mess and not right at all. I think I need to redo it/migrate? but the RIGHT WAY.

Can someone tell me the process to find the last pre 2022 COP catalog and the right way to make the catalog on COP 20 version? Like I am 10 years old please.

Just to remind: This is entirely about getting COP 20 to work. Moving from a previous version to 20. Yes, I know, it is not 21 or 22 but it is what I have and, I am fine with that.

Like I am 10 years old please.