Background

In order to extract MP3 files from Audible, it is necessary to convert the AAX files to MP3
And in order to do that, a magic number is needed - this is a 6 digit number called the Activation Bytes.

Download the following tools

git clone https://github.com/inAudible-NG/audible-activator
git clone https://github.com/KrumpetPirate/AAXtoMP3.git


Edit the audible-activator.py script, and modify the chromedriver path:
    if options.firefox:
        driver = webdriver.Firefox()
    else:
        if sys.platform == 'win32':
            chromedriver_path = "chromedriver.exe"
        else:
            chromedriver_path = "/usr/lib/chromium-browser/chromedriver"

Run the audible-activator.py script to obtain your personal activation bytes:
User: user@mydomain.com
Player ID: xxxxxxxxxxxxxxxxxxxxxxxxxx
Activation Bytes: 7b14b007

Create Conversion Script
/path/to/AAXtoMP3 7b14b007 $*