Do I need a SSL Cert for Ultimate Facebook Plugin

HELLO, I am trying to get Ultimate Facebook to work as a login option and I get this error

Given URL is not allowed by the Application configuration.: One or more of the given URLs is not allowed by the App's settings. It must match the Website URL or Canvas URL, or the domain must be a subdomain of one of the App's domains.

In the setup there is an area for a HTTPS URL is this mandatory I am thinking yes and just want to make sure before I buy a dedicated IP and SSL Cert.