Email not accepted on required field

This customer tried to make a purchase through my order form, the first 3 times, it declined his payment while trying 2 different credit cards. I communicated with the client (or lack there of, because he hasnt been able to successfully place an order), I got him try try for a fourth time, and this time is did not recognize his email address, told him that an email was required, even though he already entered his email address into the form.  This customer was using Chrome browser and Mac computer. 

Base on the screenshot provided the required error shown isn't from the email field. It is from the Select your Quantity field. It was probably prematurely shown after the user switches from the options.

Anyway, I still have tried that email in your form and it is working properly.

And here's how it appears when you submit the form without values on required fields.

Perhaps the problem was a user error, please ask your customer to try it again.

Thank you!