Pretty much what Dr. Knuckles said on the .vmf file bit. The link you provided was the source code for a HL2 mod of the game Mariokart.
Also, the author posted the map 2 years ago, but he uses GameBanana regularly and has various ways to contact him such as his email or steam (go to his profile here:
http://gamebanana.com/members/222167 and look at the contact bar on the left hand side). TF2Banana is a sub-site of GameBanana which only hosts TF2-based stuff.
Again, not trying to be rude or unreasonable, but talking to the original author is only good manners. Most times the authors are pretty chill to talk to and, unless they aren't finished with the map but just haven't had the time, they won't mind giving someone the files necessary files/materials to people that want to make a port or edit/fix their maps. They may also impart their ideas on what they planned to do with the map, but didn't have time for, which your players might love.