I got some help from a friend and we got it working. The problem seems to be that the database was not finished writing to the email table when the CiviRule fires. We switched the rule to Trigger on "Email is created".
I take it you have already read that CiviCRM is designed to work with only the following 4 CMS: Drupal, WordPress, Joomla and Backdrop.
Therefore I assume you are asking a question more along the lines of 'how can I embed a form for event registrations on a standalone CMS?'
There are tools (RemoteForm, CMRF) that allow for this but they still all require ...