This download looks like a save. You need to place it in your saves folder inside the Garry's Mod folder.
You should end up with a directory structure similar to below:
Don't know where the Garry's Mod folder is or how to extract zip files? See more useful installation tips.
caretbay47, jose-patricio_figueroa, \/endetta, MaXXL, francogallardo2006, DJDragonFree#RIPCOD, North Koreans=WW2 Russia, nakkalokesh966, koossa12344, Raven, AGRESSOR, toddortiz83, XANTHAR, m3gu$7a31p4ya$0 >:D de Astora, monitorkop4e, Heckelex, HELL CAT :3, deeginator2, ᅚ, saki, saki, WoLfIe<33, King Shringus MXIV The Great, Detective J., nongteam_seka, Murder Is Pink, SuBDivisions23, Jeffrey, Jeffrey, |-KPH-|, FeatherstoneRF
