You download the Endless Aisle source code from GitHub.
Navigate to Salesforce Commerce Cloud SSO Signup, and log in with Account Manager credentials.
If you have access, you can get source code from the following repositories:
Follow the instructions on each GitHub page to get the source.
For the latest details on downloading the app and server source code, see Endless Aisle App Source Code, Endless Aisle API Source Code, and Endless Aisle Solution - Download Source Code.
The next step is importing the Endless Aisle project.