This feat is accomplished usinig an Arduino Leonardo.
MUST USE Arduino IDE VERSION 1.6.0 TO COMPILE PROPERLY (please refer here: https://www.instructables.com/id/Turn-an-N64-Controller-into-a-USB-Gamepad-using-an/ please read: "Step 1: Setting Up the Arduino Environment")
Arduino IDE VERSION 1.6.0 Found here: https://www.arduino.cc/download_handler.php?f=/arduino-1.6.0-windows.zip