There are a bunch of different sound file formats.
Some Mac. Some Windows. Some both.
Free Audacity
https://www.audacityteam.org/ will probably be able to export most of them.
A 2.0 vs a 3.0 ripping port '
might' cause this but probably not.
On my computers I have both types, which made some USB sticks un-reable.
Make sure to try both.
Formatting the USB stick to the incorrect format can also cause issues.
NTSF is old style.
Probably use FAT32 or better yet exFAT for modern electronics.
You should be able to play at least one type of music file on the system.
Else the radio is DRM garbage and bricked itself.
(And post the brand name here so others will not make the same mistake.)