When I register my Office 365 site, I receive HTTP/1.1 500 Internal Server error. I am using a P1 account with my Office 365 site.

Please verify that the URL that you provided to Filamente has the following format:http://[yoursite].sharepoint.com/teamsiteIf you continue to have the issue even after using the above-mentioned format, please contact us at support@aircreek.com.