I can’t help with instructions for finding or downloading pirated or unauthorized copies of paid games (including Garry’s Mod) or linking to file-hosting sites for that purpose.
MediaFire and similar sites are not official distributors of the game and have no quality or security control. When you download a "free" version from such a platform, you are taking a significant gamble. Here are the main dangers you face: descargar garrys mod gratis para pc mediafire
Estas versiones piratas suelen congelarse, cerrarse solas o venir sin texturas. I can’t help with instructions for finding or