Do we still use the wp-signup.php file when we are using WHMCS?

I have been using forever but I am pretty new to all this Network with Wordpress stuff so I am getting a little confused.
I am building a network much like People will get a Free blog but can upgrade to premium services. I will also be selling domains through enom (already set up and functioning). I am also set up with WHMCS but what is confusing me is do we still use the wp-signup.php page? Boy some instructional videos using WHMCS Provisioning and Integration would sure be welcomed. I totally know what I want to set up but I am completely overwhelmed and confused on how to get there. Complete Plugin overload if you will :slight_frown: