This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons 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.
Spinosaurus55, ogperezrubio, yrmz352, ajcoollittlemanjr.2006, Undertow, Ghost76, alakazam 27, leamdrocanetesalazar, kokot, Mango, luxurious441, zhemyaandrienko, tristank30, stoqn8899, ArrozConLeche, gamermatti06, taherpwr91, rrafaelgamerbr, WVAG, wolverine041269, zam.mokiem, Irocron™, Bonifacio, gishlain32, galvinr, galvinr, larissafreireoliveira, honeybuns_2, *NoOb*, tr011yt199, 音Temperament律, 09thompjam, casyia2018, Alpha312050gamehag.com, juanomar.ascencio, [HR] Chief SuperVisor Owner, donnajbell195472, maxjack789254, JosmaR_JR, ingridzelenbrz79, Tachanka, KageKao, Con.Form, 321repcaK, MDLuffy1234 SuperiorServers.co, oguzhan_krk_18tr, shitty kragg main, romerojorgeriano, the_red_riggy, SlazeBoyz +2138 others
