Audiobooks your purchased from Audible are in AA/AAX format, you can only play them with Audible designated devices and players.
Follow below steps and learn how to convert Audible AA/AAX audiobooks to MP3, M4A, etc. with Pazu Audiobook Converter for Mac. If you use Windows, check this user guide .
Step 1 Download, install and run Audiobook Converter on your Mac.Download
Step 2 Drag&drop the audiobooks you want to convert to the Audible Converter.
Click to edit audiobook metadata if you like.
Step 3 Click Options if you want to split audiobook or change output format.
You can split audiobook by chapter, duration or to equal parts.
The default output format is lossless M4A. Audible converter also supports converting audiobooks to other formats like MP3, M4B, AC3, AAC, FLAC, OGG, AIFF and WAV. Click Options - Advanced to change output format.
Step 4 Click Convert to convert your Audible AA/AAX audiobooks to M4A, MP3, etc. with 100% original quality.
After conversion, click History to locate the DRM-free audiobook in the format you desired.