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.
Gucci-Ryguy, tommyhenrysimpson, Rudd1ger, spring215, Dam26, Odyssey, Thanx4Laughing, inu, Sonic, YunoDoesntExist, Little Buddy, davidadegbemijo, Yoto, Marilyn , Demo 152, OKok, webzine114, Mexcur, Der König des Pharaos, BaSsI, Mr.Skeltal, Dartz.Wav, Hamburguesaqueso, Skin Investor, Mezitable, bryek, [X], OhNoPup | Twitch, Nanoo, cristina.niculae2014, Heksnam, Fer, Aixode, Yikers, KayyCeeTV, Amon, ElFilho77, steve0_camacho, -d, Ace, Creepyimpost, BANNED4EVER, MelodyCammy, Mr_savageDC, unaicuentaiverificada, hamomeddu78, Infamous_MySsTiC, maxlaberge9, ♛ Allpatino, AGScorpio +25013 others
