The maps and road logs on this shopping cart should be self-explanatory. When you buy something, you will create an account for yourself and it will have your download links and a record of what you bought. You also get an email with download links, or if you bought a book that needs to be USPS mailed, you will get a confirmation. Your GPS orders will also generate a confirmation page.
But, if you do need to contact Mike about an order, the best thing to do is to go to Mike's web page contact form - http://www.mexicomike.com/contact/pre-contact.html