I'm really confused...

I just did a fresh install of v1.50 and now I need to install a USPS module. I downloaded this:
http://www.zen-cart.com/index.php?ma...oducts_id=1962

But it seems to be only an upgrade, not the entire USPS module? The install.txt also seems to assume you are upgrading a previous USPS module - but in v1.50 I haven't got a USPS module??

How do I do a fresh install of a USPS module on v1.50?