I need to add a form to my website which collects a users name and email, then accepts payment via credit card (to square if possible), then when the payment is complete make an api call to another server, passing the name and email. The call to the other server will include a secret, so it should be made from the backend of squarespace. I am long time full stack developer and have developed similar things on wix and woocommerce, but not sure how to start with squarespace. Can anyone direct me at some resources? Or, suggestions given the limitations of squarespace?