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.
agustinrome007, 9 night, tifluvsu80, , caretbay47, Капрал 114, jose-patricio_figueroa, soundwave, nice sai pose, MaXXL, francogallardo2006, JackGaming 0-88, DJDragonFree#RIPCOD, Elemental Berserker, LMB Soldier, nakkalokesh966, koossa12344, Raven, AROGANIT, loki, toddortiz83, XANTHAR, m3gu$7a31p4ya$0 >:D de Astora, monitorkop4e, Heckelex, grosjeanfis, HELL CAT :3, deeginator2, ᅚ, beato, beato, WoLfIe<33, King Shringus MXIV The Great, Detective J., nongteam_seka, Murder Is Pink, SuBPai, Jeffrey, Jeffrey, |-KPH-|, FeatherstoneRF
