I'm getting an error that only one entry is allowed

 Sorry! Only one entry is allowed. Multiple submissions are disabled for this form.

what's happening.

The error is related to the Unique Question Limit. You need to disable this by selecting "No Check" from the option. Here's our complete guide for this feature: https://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question.