You need to connect the display to the PC using a USB cable, if this has been done and still PC connect doesn't detect your display, try connecting to a different USB port or check the USB connecting cable, it might be faulty.
As mentioned by others earlier, if you use a smarthub, you don't require a display to communicate to myAcurite. But connecting the display to your PC helps you to download and save your weather data on your local PC