It has been a while for me since I last ran Mint, but back in the day it used to come with Brasero which can burn audio CDs. It would have supported mp3's, but he would of had to install the non-free codecs which was an option at install time or would have been installable from the settings.
I can't speak for Linux Mint, but last few times I tried to use Brasero it was issue after issue after issue with some kind of lower level driver thing. I installed the missing libraries, still nothing. Tried searching for a fix and found nothing that could resolve my issue with Brasero. I installed K3B and it just worked, so that is what I do now.
Possibly the parent poster's uncle ran into something like this and gave up instead of trying a KDE application?
I can't speak for Linux Mint, but last few times I tried to use Brasero it was issue after issue after issue with some kind of lower level driver thing. I installed the missing libraries, still nothing. Tried searching for a fix and found nothing that could resolve my issue with Brasero. I installed K3B and it just worked, so that is what I do now.
Possibly the parent poster's uncle ran into something like this and gave up instead of trying a KDE application?