Error - Cannot use Nintex Forms for content type : Event

I am trying to create a nintex form for the default calendar app in sharepoint since I need a form, nintex workflox, and the ability to connect to an outlook calendar. Problem is, the default calendar has columns that are used for an "event" which is creating the issue in nintex forms. I created a view without using any of the "event" columns and nintex form is asking me to upgrade. When I hit upgrade, I get an error message without a code.