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.
Open Steam, right-click Garry's Mod in your Library, and select Manage > Browse Local Files . DESCARCД‚ FIИIER – MOD.ZIP GARRY
Only download .zip files from trusted sources like GmodStore or reputable community sites, as manual files are not verified by Steam. Manually installed folders are known as "legacy addons