The Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter requires a host that supports Thunderbolt 3 over USB-C.
If you’re having issues with the adapter, or if you were directed to this page when you connected it to your computer, verify that your system supports Thunderbolt 3 over USB-C. Check with your system’s manufacturer if you think the message was shown in error.