Ah, this was my mistake in wording — I said "API," but I really want to know about PayPal Website Payments Standard integration. We do not have a particular need for Pro, but have access to Standard (as opposed to Express) and would like to use that to accept credit cards through PayPal from customers who do not have or need a PayPal account. We have done this in the past with many other ecommerce systems, but don't see where to begin to set it up in AliCommerce.