Creating a website for clients to create their own site using a subdomain of you

So I would like to create a wordpress multisite, but the main website should be a registration site where clients are able to create a new website using pre-made templates that I created. I want them to be able to choose a name for the site, subdomain (if it’s available), and a template. As well as an email and password registration.

When that’s done, I need the client to be redirected to their sub domain website with a visual builder that allows them to edit and replace certian content on the template to their linking and publish it.

Can someone give me advice on how ai can accomplish such a task?