Quote from the first exercise:
Note: This unit is optional. We'll walk you through the steps required to purchase a custom domain name and assign it to your GitHub Pages site. If you do not want to purchase a domain name, you won't have to. However, feel free to follow along to see what steps are required to do so (for future reference).
I see Amazon has what is called the AWS free tier service, would that help me getting a free domain or it's just for something else.
It's for something else.