Hello amiase simeon . Using route 53 wasn't explained because it's not the focus of the article and it's an easy step.
Once you have your domain, go to route53
- create a hosted zone with the domain name
- if the domain is not from aws, add the 4 NS from the hosted zone to your domain provider custom NS.
- then on your hosted zone, proceed to create A records for the sub domains required for these projects. The A records should point to your public Ip.
I hope you find the steps above helpful. If you need further assistance you can reach out to me on X. My handle is @drintech22