"There is no sign up!" (except this one if you want to participate in the User Support Forums).

b2evolution is not a service that you can sign up to and make your site with.

b2evolution is software that you install on your own server (which can be shared hosting, a VPS or a dedicated server). The advantages of this is that you have full control over your content and your user data. This is also paramount in case of intranet installations.

If you were looking for a "just sign up" service, sorry, b2evolution CMS is not the right tool for you.