This unit plays audio files as follows:

CAUTION
Do not use an audio file extension on files other than audio files. In addition, do not change the audio file extension. Otherwise, the unit will not recognize the file correctly resulting in noise or a malfunction.
NOTE
MP3/WMA/AAC/OGG files written under specifications other than the indicated specification may not play normally or files/folder names may not display correctly.
Operating Tips for OGG
Audio SetMazda 6 Owners Manual: Rear door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the rear door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Rear Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...
Mazda 6 Owners Manual: Automatic transaxle removal/installation
1. Disconnect the negative battery cable.
2. Remove the battery and battery tray.
3. Remove the aircleaner component. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
4. Remove the front tires and splash shield.
5. Remove the under cover.
6. Remove the steering gear and power steering pipe. (See ...