Above is from the manual
https://www.google.c...ln9lojPtOsIWic6
As you can see MP3 is not one of the formats it expects. You can convert MP3 to MP4 if you really want to go to the trouble.
https://onlineconver...mat/mp3-to-mp4/
This was just the first one I found.
You have to upload the MP3 file then once it finishes you download the mp4. I just tried one to see if it worked. Apparently you can do multiple files at one time and download them all at one time as a zip. I'm hard of hearing so can't speak to the quality of the conversion but I was able to play the resulting mp4 file in VLC. You just get a black screen. Probably if you look around you can find a way to add still pictures. This one looks promising tho I haven't tried it:
https://www.fileconv...-mp4-converter/