If the download is a .gma file instead of a .zip , you must use gmad.exe (found in the game's bin folder) to extract it before it can be used as a manual addon.
Ensure the folder name has no spaces or capital letters, as these can sometimes prevent the mod from loading. Important Tips for Manual Mods DESCARCД‚ FIИIER – MOD.ZIP GARRY
Manually installed folders are known as "legacy addons." If they don't appear in-game, you may need a tool like the Extended Spawnmenu to browse their models easily. If the download is a
Only download .zip files from trusted sources like GmodStore or reputable community sites, as manual files are not verified by Steam. Only download
Drag and drop this extracted folder directly into the garrysmod/addons directory.
Open the garrysmod folder, then open the addons folder.
To manually install a Garry’s Mod addon from a .zip file, you need to extract its contents and place them into the game's folder. Quick Manual Installation Guide