Connect your Duet to your PC with the USB cable provided. Do not connect any additional devices or PSU

Windows: Download and extract the USB files from here

Open Device Manager by right-clicking on the Start icon and click on "Device Manager".

Look for any device with a yellow triangle or "generic USB". This indicates the Duet driver is not installed.

Right click on the device. Click Install Driver and browse to where you extracted the downloaded driver files. Click "Next" until the driver is installed.