Member by Automated Selling comes with a free sub-domain URL like "default.memberapp.io" which you can use if you do not have yet a domain. You can change this to use your own custom domain URL. To learn how to customize your own domain, please click here.
To use the default domain
Start by creating a course, and in the course details, enter your chosen course name and enter a domain name. Leave it set to "memberapp.io"