With a creative product, the first thing that happens at the checkout is that the emotional brain says that you want the product. It’s pure emotion. And if we go ahead and buy it, then afterwards our logic brain steps it. It will tell us why it was a good idea that we bought the thing.
During the process of buying, however, your logic brain will be screaming that you don’t really want that thing. And the longer and more difficult the process between deciding you want the thing and being able to complete the purchase, the more likely it is that you will just abandon the purchase.
All the studies say this is what is happening inside our heads. From personal experience I know it is true; as a customer I have done that exact thing many times.
Every demand you make of your customer in order for them to complete the purchase makes it more likely they never will.
A good platform is one that speeds you through the checkout process. The Shop payment system from Shopify recognises you as soon as you add your email address. Apple Pay and Google Pay do similarly. Add your details once, and then it knows you whenever you check out.