How can individual sites allow user registrations


Ok so I’m a noob. Trying to figure out the multi-site features.

So If somebody has their own blog on my multi-site they want the ability to have users register on their site. When I have in network admin ability for users to register it goes to my main register page. I don’t want that. I need to give my blog creators ability to have users register on their site correct?

Am I missing some core functionality of how the multi-site works? Especially if a user has their own domain and I’m using custom domains I’m thinking I don’t want their users to register on my main blog multisite register page?