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.
misterpes #SaveTF2, gzilka98, Slpk, shyfulReverie, yopt755, Bad Elite, we222222222, Billnye The Russian Spy, arayafelipe623, b0rk, Tyrannotitan Fan, Tyrannotitan Fan, obibest2016, Player, aszxcde1234, ramsveenbalaba, seancondino05, Tracy, mossesx, just a chicken cosplayer, undo, F2P Soldier, Travis nowhere, neprest87, BokMustang, lukedavi, josemiguel_navarro, Bedrock™_HEAD, (Arqu), Foster [TR], re15revisited, Detective MAGNUM, vonmaisa, WareWilly101, sawyer13, Heavy weapons guy, NUKABREAKER, Z_A_R14, ryslanchikkk, Spectre, aeiouoiea, goodoldund, NooB, theAwesomeSponge, Grizzly, Kasparas Ražukas, sleazenglamroxx, demonsoul, SistwoCC, bad_grandma +13 others
