WHMCS error w/ Virtualmin OpenID Connect requires a Certificate Authority verified SSL certificate. A verified certificate wasn'

Virtual domain exists with a valid SSL. WHMCS and OpenID can’t seem to find it. OpenID and WHMCS seem to want to discuss CPanel. Pointers, Docs, etc would be helpful as I see this as a good tool to have available.

TIA for your help. UBUNTU 16.04 - Virtualmin PRO