If you're having issues checking out, please contact our customer support team here: loot.cr/support
Other suggestion is to update your payment method. Login and go here to update your payment method:
https://lootcrate.com/apps/checkout/l/account_info/
Under Payment Information, you will see the option to select Manage my Stored Payment Information. From there, you will need to re-authorize your Amazon Pay or update your payment method to Paypal or a credit card. After completing this part, you should be able to check out!