Music files in AAC format cannot be played. They cannot be loaded to a crate and/or a deck.

QuickTime of Apple is needed to play the music files in AAC format.

Please install QuickTime into your Mac.

After installing QuickTime, launch Serato DJ Pro and untick "Show iTunes Library" in Library + Display on SETUP window on Serato DJ Pro.

Then, tick it again to start using these files.

Please update iTunes to the latest version.

Also, please see the FAQ in the Serato website.

iTunes and QuickTime are trademarks of Apple Inc., registered in the U.S. and other countries.