They'll be in M4A format.
They need converted to MP3 I think.

 

I use a Windows PC so not sure how a Mac formats.
What format is the USB stick? It needs to be FAT32 or exFAT.
What format is the music? I've found MP3 works on a USB drive although WMA, OGG and FLAC are also valid.
How have you formatted the files on the USB drive? Mine are in the following folders: Music/Artist Name/Album Name/Tracks. For example Music/10CC/Best of 10CC/01 Rubber Bullets.mp3
I use a programme called MusicBee to manage my music and it puts the artwork into the file metadata so I don't need to copy the album artwork over.

PS I should point out that encoded MP3 files won't play.

 

As mr.mac already posted - FAT 32 format usually works ok.
I had this trouble many years ago and as soon as I formatted the usb to FAT32 - all ok.

 

Recorded music from my iMac and l have checked the drive on my computer and it does play but not in my car. Am l missing something here.

As ‘mr.macspot’ has signalled, ‘Graham J’, if your USB drive is set up for a Mac, you need to go into ‘Disk Utility’ and format a blank USB drive to Fat 32. Once you have a clean, formatted drive, you can transfer your music on to it and it should play without any problems.

I’m not sure how familiar you are with formatting on a Mac but please don’t attempt to change the format on the drive with the music still on board. The process will delete everything on that USB stick! You would need to transfer the music to a folder on your Mac desktop temporarily if you don’t have a blank USB drive. I’m sure you know all that but I mention it just in case! 😇

 

Thanks guys