How do I integrate square payments so they must pay before form submits?

Hello,
 
Thank you for contacting us.
 
I understand what you need, but unfortunately it is not possible to complete a payment before submitting the form.
 
This is because the redirection to the payment page is triggered at submit only. 
 
Please do not hesitate to contact us for further assistance, we are always ready to help.
 
Kind Regards,

Hello Yoshi,
 
Thank you for your response.
 
As a workaround, you can set up to receive the email notifications only for the users who completed the payment.
 
Here is a screenshot to guide you:
 
 
Please let me know if that would help.
 
Kind regards,