Upon submission the return is "This form is currently unavailable"

Users are able to fill in the form and hit apply, once they do the error "This form is currently unavailable!" is shown and the data is not collected.

That's because you have set a limit on submission, once on the edit mode of your form:

1) Click on Preferences

2) Click on Form Limits

3) On Submission Limit, remove the number and just leave it blank

If you need anything else, please open a new thread, we will be glad to assist you.