Virt manager is the least intuitive (discounting actively antiuser crap) program I've ever dealt with. I still don't quite get it and I've used Linux exclusively for more than 5 years.
For anything more complex (e.g. GPU passthrough) you will need to drop into manually modifying XML files.
(user group setting issue is a common hiccup)
It pretty much just automates the standard Qemu/kvm setup workflows. =3
I just started using Incus now. It seems way more intuitive. Its remote feature is amazing too.