Help me with a ringtone

I have a dumb phone (Pantech P7040P), and I’d like to get a new ringtone. (Specifically, the old rotary-dial phone ringer.) I found an mp3 file and saved it to my desktop. I connected my phone to my computer via Bluetooth, so now the file is on my phone. But apparently my phone can’t use mp3 files. (‘Set as ringtone’ is greyed out.) It can play a .mid file; but I’m not sure my MacBook Pro can, so I won’t be able to hear what a file would sound like until I put it on the phone.

Is there a way to convert mp3 to midi? (i.e., using a tool that would be on a Mac.)

Never mind. I found an online converter.

ATT says your phone uses .mp3 files. Are you storing the .mp3 file in the correct location on your phone?

I don’t own a Mac but a simple Google search reveals quite a few converter tools.