There is no such thing as a zip file that is only compatible with the CS. I think you are trying to run the zipped file from the site instead of downloading it.
If you use Firefox, When you click on a file to download you should get a pop up window with a What should I do with this type question - if open is checked it will try to run the program from where it is. look for a save to disk option and select it.
It's been so long since I used MS Internet Explorer I don't remember how it works.
I have written a set of short tutorials for people new to mods. starting with how to download, what the various form of zipped files are, how to unzip - with a link to a free unzipping program (7-zip) that will work with all of the zip formats used on Tesnexus. Then how to get your unzipped file into your game plus some troubleshooting. It includes a small mod that can be downloaded from Tesnexus to use for testing. To go to the tutorials click on the highlighted text.
http://thewormhole.nfshost.com/forum/index...opic,296.0.htmlYou may be asked to register, but it's free.
The test file is small, does not change anything in the game and can be erased at any time - it's good for troubleshooting download problems.