wma files are not included in the list of acceptable file extensions in the manual.
The system also only supports FAT32, NTFS, and HFS+ file systems.
Windows will rip cd tracks to mp3 format (wma may be the default, but you can change it to mp3 before ripping from the cd.)
As long as you have a FAT32 formatted drive filled with mp3 files, you should be good to go.
2015 Chevy Equinox LT AWD 3.6LV6
Sea Grass Green