Why do users keep getting an error after submission?

Hi, when users fill out a form, regardless of the address the put in, they're receiving an error message that says "Sorry! Only one entry allowed." even if it's a new-to-the-system email address. 

Please make sure that you disable the Unique Question feature and the Unique Submission feature. Please set it to No Check option to allow multiple submissions.

Give it a try and let u know if you have questions. Thank you.