A:Answer "file format not supported" probably means, that the file is not a mp3 file, probably a M4a file that the device cannot read, or does not understand.
There are programs (or maybe windows can do it) that can convert non-mp3 files to a mp3 format so the device can play them.
I have a similar file, but I have not taken the time to attempt a conversion to a mp3 file.
That is my understanding - but I am in nooooo way a techie!