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.
Glitch Trap, superidolggg21, #HEAVENRUST Транцплин, cherry, samu6, Batu Bey, BIG HEAVY, LeiGacha2468, alain.hung, Hassan aus Wellenstein, Scorpio, xplay.gg Darius, Adidou, joacopouso, cleiton222343, I love virtual women, Snowbie-Na-Nobie, ., winntucker58, winntucker58, giorgialeksishvili327, ACEMEISTER, ironjab, MonstruousGamer, MonstruousGamer, BusEspionyt, Daniel Larson, nagoyashi0407, ZOZO, mohym806, Fazzzy260, Anis_1916, kahlebarnold1, Ionutz Camataru, MrRubRub, kaysilminer, Spailo, ggspeedruns, LIErZ, kiler, BlueBurrito, SIB, da.silvan8305, xiao_zhou, andrew.szanto3.0, aleiberorellana9, xzangsx70, uncanaldetodito21, krasnyy66, UncleTonyv2 +5599 others
