AWeber is a service that helps you manage email subscription lists. The Easy Digital Downloads extension for AWeber helps you connect the service to your store, and allows customers to subscribe to your email lists on AWeber.
The configuration settings for EDD AWeber are found on Downloads → Settings.
AWeber Authorization Code
The first setting is an Authorization Code. This allows your site to communicate with your account at AWeber. Next to the settings field is a direct link to get your AWeber page for getting this key. If you're already logged in it will take you directly to a page telling you you've authorized Easy Digital Downloads and present you with a key which will be a long string of seemingly random letters and numbers.
Show Signup on Checkout
If this option is checked then at the bottom of the checkout form the customer will see a checkbox with some text indicating that if they check it they will be subscribed to your list. If the customer chooses to, their email address will be subscribed to your list at AWeber. See below for text setting.
Choose a list
You may have many lists created on AWeber, but in this settings box you must choose the one that your customers will subscribe to.
This allows the site admin to set what will appear next to the subscribe checkbox on the checkout page.
Download Specific Settings
When editing a specific Download there will be a meta box on the side labeled AWeber. It will show all the email lists available on AWeber, and the site owner may pick one to be attached to this Download, and over-side the global setting.
This means that when the customer checks out, they will be asked to subscribe to THIS list, rather than the one set in the main AWeber settings. This allows you to do things like set up a custom list for each product, and build an email list just for each product.
Once you have a list built up for a specific product you can email that list with new releases, security issues, etc.