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.
AnHumanError, bojan.milenkov745, javier2410a, klaczek200, mixiium, [SSSL]BADOLON, ElCocosHQ, XRakzhon023, smecherescu, annoyingmikamail2, T-Bone, guculakdenis, ggderk, hubert.ossowski2014, jddv15d, dennis.botinis, herobrine77y, Dark29086903, DANIL3L_15, jonathan.gp11, Neptune, JammyBarry, Fox2435, IGN|Technokill900, KillingMaserX, Petuto17, M3rlinwashere, Granti, &&&&&, pelajartua.123, Corporeal Cracka, gyyhh016, solcelestial, cipher192, Mr Fat Yoshi, brabra, Silent Ammo, Magic Man, alessiopicarella, i like cheese, Lushtub, hwasunkang7, Radek gamehag.com, gabrielkrauss98, realegianmarco05, nwmann, BTMayo, ADM Elcolo, garzanancy, robertocarlosrcrb03 +4759 others
