If you open the SAS Grid on AWS page you are redirected to AWS website. At the very below there is a link to git-hub page that has the source code for this quick-start. I have highlighted it in yellow in the snap below. This source code is where you will find the information regarding what cloud-formation templates are being used to spin up abc machines with xyz capacity.
If you are new to this I wouldn't advise you to make any modifications as the quick start will automatically bootstrap everything you need to have a SAS/Grid cluster up and running.