This download looks like a map. You need to place it in your maps 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.
Felix, lautarorodrigo2010, facuvillaher, Graf, Mr_Deus, wavymahmah22, luisDrone, noobsaibot1997, chavezdavud2008, pizzaboy420, titanartix123, Mr Shadow, simontamasgaming, minecraftiendu803, yam.oceans | trade.tf, kubuskazanowski, brandonjanusek74, nursultan62chab, Sonny V, Harambe Uchiha, Wolf [139], Civilgamers.com Greeny, ~_~, ~_~, joelholmes454545, SSGameplayGabor, Clexome, Timse_333, DaniloYT, Buck, Zac ATK, ✠Вода SS✠, Mr.Freeman, ุ Hatemus, stepankashar, FD GOD, DanVoin, dropthezombie2, CaptainColeNew, Darth Vigorous, mossesx, poil60, Cat 47, iDramaGFX, [AU] Nexys09, packin.ilya, Crowe, Actually, «Erlox», [PN] Stormcloak787, muscatura2122 +129 others
