Vat questions and confusion

I had a guy ask for a vat receipt I was under the impression amazon would deal with that since they shipped it. But anyways I got this violated policy email since I never sent the receipt even tho I was still trying to set it up. During the email it links to an automatic invoice generator. Once I click on it and can’t activate it because I haven’t selected “default country for a VAT exclusive” but when I click on it nothing scrolls down. I have selected and added a VAT registration number