In the past (and still, on mobile devices) one must go to the aa.com shopping portal, signed in, and shop from there to earn AAdvantage miles through the Cartera e-shopping program. As announced in e-mail today:
You can now install an “AA Shopping button” on your desktop for easier e-shopping and AAdvantage miles raining.
Link.
“Benefits of adding the button for desktop
- Never forget to earn AAdvantage® miles
- Activate earning right on stores sites
- Compare mileage offers in search results
- Easily view your recent earnings”