
It's not what I was looking for, but I have answers for some of the problems people have had. I'm on Mint 21.3. It wouldn't launch at first, but when I tried to run it from the console I saw that I needed to install something.<br><br><code>flatpak install flathub org.gnome.Platform/x86_64/44</code> took care of that.<br><br>Then, to solve the problem accessing other folders, I used Flatseal.
it does not work at all. you can install it normally, but when you try to open it, the programme dose not open. I’m using Mint 21.3 Cinnamon
Regarding the problem of unable to add folders to the music library: the default version delivered with Linux Mint is a flatpak bundle. This is the reason that it cannot browse the entire filesystem.
I think this is the best music library for linux. Unfortunately I couldn't add any folders to my library in this version. I currently use Linux Mint 21.1 Cinnamon. I downloaded version 1.1.99.1 with gtk3 from gmusicbrowser.org and it worked fine for me. I would recommend you to do so as well.