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.
*-FearEngine-*, stephen91, joalalfred21, asasynx5, Hierophant0, MacBareth, Skow20002, [Naruto:RP] Uliek, V.1, batuhanaga6575, juliafrank1974, RAIZERtag, johnguzman9696, [WOC]Wallace, #PayForHarambe | Yadon, Airnax, paulpeyrot.stjo, shadoko75, WhyPok, ▒ ♛ ριєяяє ♛ ▒, PGAL~ZaRTaX, nayarit555, Link, godlyknight84, Lillewolf, Tebra, ☭Kura-✞-Givi☭, Speedy, Luke8163, RustyRhydon, DerpyS, cakmantayyip, Saysay, karman02, Minou Explosif, Just Me...Yato<3, xXFuRo3iDoXx, Yagura, Grypho, toxicity997, Nev674, Kazh, PURGE000, piplup_the_panda, noam.mojang, ondrej147ak47, Kafaldsbylur (Alex), EatMyRainbow, Infinity., SpoonKiller30 +170 others
