Alright there's this one thing I've seen that's been bugging people alot when downloading mod maps. Some people zip their files into rar file format and not everyone's computer can read those files. If you've been having trouble with this you should download
WinRAR free trial which will be able to read and extract these files. It's pretty helpful. For full details about it visit this site
http://www.rarlab.com/index.htm.