Unable to Disable Free Auto Signup Feature

Looking for solutions to disable the free auto sign up feature in HC8. The check box is greyed out, and therefore I am unable to disable this. I believe this is the issue as to why I am getting an error once a user has finished inputting their information at the signup page. The error displayed after they select their plan and input there details is: "Error Occurred while completing auto signup"
 
I do not get this issue if I change the auto signup feature to Authorize as opposed to Capture.
 
I have attached an image of the issue.
 
 

I have no issue in setting up free signup option, it is visible in my panel.