Open file manager, go to your downloads folder, and then right click on the 'Launch' button and click 'show in file manager', then open 'bin' (in the rigs of rods file) and drag your mods into 'content'.
If your GPU doesn't support opengl 3.3 you'll need to get a newer one. My AMD Rx550 factory overclock isn't the worst when it comes to RoR, and it cost me only $155 CA.