When I send an email with an attached fillable form to a coworker, the submit button doesn't work when they complete the form.

I created the form in Adobe Pro, programmed the Submit Button based on program requirements, and saved the form. I sent test emails with the form back and forth between my Outlook account and my Gmail account. The form worked fine, including the Submit button sending me the completed form in a complete .pdf just as I had programmed for the button. When I sent the form to coworkers using my Outlook account, they can complete the form, but they can’t Submit the form. Please advise on possible issues that would be causing this. 

We have tried other browsers and downloading the form first. Nothing has worked. I have attached the error message my coworker received.