Having an issue running an Arduino sketch I just got my USB host shield attached to my Arduino Uno, opened the program sketch for USBDESC.ino and I'm getting an error. It says "usbhub.h not found". It won't compile. How did I go wrong?

I am using the Mac version of the Arduino IDE and downloaded the USB host shield Master v 2.0 file directly into /Arduino/java/examples. This was how I have added every previous library download. Please help. Thanks.
I don't know how you came up with that location as the right place to put libraries. It is wrong. Oh so very wrong.

Libraries go in ~/Documents/Arduino/libraries as stated in the first hit for "arduino macos libraries" on Google.