I've downloaded an add-on for my shipping software ECC that is compatible w/ CS-Cart 3.x and 4.x. It is not written in the proper format to install to CS-Cart 4.x automatically via upload on the addons page.
Assuming it is truly compatible, how can I install it manually to a 4.1.x site? I'm doing this on my test site, so it's OK if it messes everything up.
I figured it out. It's not a real add-on. It accesses the database directly without using CS-cart functions.