Having trouble deciding the optimal architecture

So I am working on a product which is B2B. The landing page of our product is eg. example.com. And once someone purchases the subscription(let's say org1 purchases it) it we ought to provide them a custom web dashboard which can be accessed through the URL (org1.example.com) . Now i have some questions about this-

Can we make this subdomain available only to the org1 members and not make it publicly available? I am a novice but can we use concepts like Route 53 Hosted zone using Client vpn endpoint or something like that?

If it is possible, is it also possible to attach one SSL certificate to this domain?

Anything would be helpful.