The Zwift Companion App connects to the Zwift app across your local network, not Bluetooth. You need to make sure that the device running the ZCA and the one running the Zwift app are connected to the same router.
If you are just trying to connect the Kickr to the Dell running the Zwift app you need to make sure it is running the latest version of Windows 10 and has Bluetooth 4.0 or higher with the most recent driver. I would suggest an ANT+ dongle with a USB extension for a more robust setup.