Can I put the same music I have on my 6X solar on my Descent Mk2

I have had problems putting my music on my Garmin Fenix for months. I have CD's that I have copied to my server in AAC, (Apple lossless compression). It seems to load 2.6 GB of songs onto my device taking several minutes but the songs are nowhere to be seen. I am loading them as individual songs, not as a playlist. By some fluke I now have most of the songs on my Fenix 6X solar installed via the new MacBook M1, but there seems to be no way to get these same songs on my Descent Mk2, whether I use a windows computer or a Mac. there has to be some work around. I refuse to buy music twice!

I hope someone has a work around.