mp3's on usb drive

I have a usb drive that I recorded 400 mp3 songs on using Windows 7. It works fine in my Jensen Radio/dvd/cd/player in the trailer using the usb port. I wanted to make a back-up copy and copied the entire drive to a new Fat32 usb drive on my new Windows 10 computer. All the files are there and will play on my computer but NOT in the Jensen player in the trailer. Any ideas on what I need to do to make the files recognizable in the trailer?