What happens after you choose
No account, no form. Stripe takes the payment and collects the delivery address, and nothing is charged until you confirm it there.
Posted to the address you gave Stripe. The code comes in the envelope and by email, and it is what puts the labels on your stock. Your receipt arrives as soon as you pay.
There is no sign-up form. We open your account when the payment lands and email you a link to choose a password — or you use the one you already have. Then stick a label on a parcel, set where it is going, and the person waiting gets told when it actually arrives.