Official comment
@James > You're likely receiving that error because you haven't fully updated to the latest (and final) Windows 7 service pack and system updates. Once you have, you won't get the issue regarding driver signing.
@David > You're likely having an issue with the OS security blocking the drivers; follow these instructions:
- Disconnect the USB from your hardware.
- Download the drivers.
- Open the driver package and run the uninstaller file.
- Reboot your computer.
- Open the driver package and run the driver installation file.
- After the installation has completed, give the drivers permission if necessary (High Sierra and Mojave).
- Reboot your computer.
- Connect the USB and test as normal.