All you have to do is visit this link to see if you’re eligible and install the browser extension.
Here’s what the Amazon Assistant will do:
Amazon Assistant is an off-site experience that puts Amazon at your finger tips even before you come to Amazon. When shopping online, it helps you find items you are looking to buy faster and make sure you’re not paying more than you have to. Leveraging Amazon’s extensive inventory and low prices, Amazon Assistant shows you contextual notifications throughout your shopping journey with Amazon’s best offers.
The Assistant extension will ask to gain permission to view your browser data before you install it. Once installed, your next order of $25 or more initiated through the Assistant will see a $5 credit applied at checkout.
Amazon says the offer expires on July 30, 2019 at 12pm PT, while the $5 credit expires on August 2, 2019, at 12pm PT.
Again, you could theoretically install the Assistant, place your order with $5 credit, then uninstall the extension if you decide you don’t want it anymore.