If the books aren’t listed in Manage Your Content and Devices on the website, while on that page, go to “Your Orders” and then “Digital Orders”. Look for the purchases there. If they’re not there, that’s not the Amazon account you used to buy them.
If the books aren’t listed in Manage Your Content and Devices on the website, while on that page, go to “Your Orders” and then “Digital Orders”. Look for the purchases there. If they’re not there, that’s not the Amazon account you used to buy them.