What when you tried to use it? (e.g., file not recognized, audio playing incorrectly)
The file probably refers to a demo song, rhythm, or recording function. Look at the RockJam manual to identify how to play, stop, or record MP3 files. RJ433161.mp3
Ensure the USB drive is formatted to FAT32, and the file is in the root directory for the keyboard to read it properly. If this is a Ruijie Reyee Access Point: What when you tried to use it