I was able to install this module, but one problem. @ the checkout_confirmation.php page it doesn't add or calculate the shipping from the checkout_shipping.php page. I checked my admin > modules > order total to verify the order:
Sub-Total 1
Shipping 2
Tax 3
USPS Shipping Insurance 4
Total 5
Also, made sure the sort order was enable for USPS Priority Mail Flat Rate Shipping to 1. So I don't know what happened. I also added the USPS Shipping Insurance module, and that's working fine. So I need help to understand what happening.