If you look at the "paths" in WinZip, they should begin with "runtime." If they don't, you'll have to place the files manually. There's a FAQ at the top of the page that explains where things go.

Another problem you might run into is that many freebies require a purchased item in order to work. For example, a lot of the "clothes" in free stuff is not actually clothing. It's textures for clothing. If you don't own the clothing the textures are made for, you can't use that freebie.