The last page should say "Thank you. Your order has been placed, and you will receive an email shortly with the details of your purchase."

To the right is a link that says "Order Status". Right click on that to open in a new tab. That will contain your order number, which should be enough for you to resolve any problems with your order.

I haven't received my email yet, almost 15 minutes after ordering, but I will be saving a copy of that order status page...