you are combining 2 different file types
in order to use it with folders, you would have to burn whats known as a "Data" CD. with this you can put anything on the cd that will fit within the *usually* ~700mb limit of the card. whether its pictures, mp3 files, video clips, what ever. you can put strickly mp3 files on here, but i don't think it will read a data type cd. whether it is sync or base.
the other way, which is how music is usually burned onto cds, is by burning it with just the music files on it, lasting within the given *usually* 80min limit, and i'm almost certain the mustang will read these whether is has sync or not.
i know this doesn't really answer your question, i mainly just wanted to clarify. i say check the manual