WHMCS Installation Not Recognizing WordPress Multisite Plugin

I’ve recently installed whmcs with my pianoteacherpro.com website. I’m going through the directions and I installed the WP multisite integration plugin, then added my HOST URL: (not sure if I added the right URL) which is http://www.pianoteacherpro.com/portal

When I go into my WHMCS installation and go to the addon “WHMCS WordPress Multisite Provisioning” the status box just says “Not Installed” when of course it is.

How can I get WHMCS to recognize the the WP multisite plugin?