Set up user account vs site registration for multisite

From the main page, users have the option to click on Login or Register,
When you click on Register and enter in all your information, you then have the option to create a username or create a site. I am trying to set up a multisite network and I want my users to be able to create their site but I also want users to be able to just create a regular login page for those who are not interested in creating an actual site. This way they can view purchase history, track their orders and such.

The issue is once you click register, if you click on create account and log in, it takes you to a page similar to that of those creating a site even though you click on "give me a username" It lists all the sites available and gives customers option to add a site. This is not a user account, can you help?

I just want those wanting to create a site to be able to select that option and be directed to the appropriate page upon login

While those who are just shopping and not creating a site can simply have access to their personal account with account history and such.

(P.S, I am using the "Cartsy" them)

I thought if I purchased this it would fix the issue but no luck. Please help me.
Thanks.