I created a form with Paypal integration - user is getting error message

Hello,

Can you review?  My integration API says it "integration successfully tested" but an "Invalid Configuration" message appears when my wife tries to test payment.

https://form.jotform.com/50983628182160

I have just reviewed and tested your form. I did not have any problems submitting information. Can you please verify the the USERNAME, API KEY and PASSWORD are correct. Also please verify if you are using the sandbox to test the form or not.