OK, so by "main Arduino folder" you mean the Arduino IDE installation folder. That folder certainly still does have a hardware subfolder. I don't know what's going on with your installation. Which version of the Arduino IDE are you using? Are you sure it's installed to Program Files\Arduino?
Regardless of any of that, you should never install anything to the Arduino IDE installation folder because it will all be lost when you update to a new version of the Arduino IDE. Instead you should use the sketchbook folder, as I explained in my last reply.