Getting all MP3s on Android and be able to listen to them

I'm an avid music lover, and over my long life collected many rare CDs. I made MP3s of these CDs and had happily listened to them on my iPhone using iTunes. This week I switched to Android (Samsung Galaxy s10e). I painstakingly uploaded all of my Music folder from my Windows 10 PC onto Google Play Music using the Chrome extension. Only 3/4s of my MP3s successfully uploaded. Under Google Play Music > Settings> Music from My Computer, there's no mention of any failures. After a quick look, it seems that the rarer recordings were the items skipped. These recordings are not in Google Play Music's library, so now I'm fearing that I can only upload MP3s that are in Google's database. **Questions:** 1. Can anyone confirm this theory? 2. If it's true, what can I do to get all my MP3s, as they are, onto this Android phone and be able to organize them into playlists and listen to them?