Hi,
Welcome to Microsoft Community Forums and thank you for posting the question. As per the description, you are unable to get the fingerprint reader to work on Windows 8 64 bit.
I understand it must be very difficult when things do not work as expected. Please answer few questions to narrow down the issue.
1. What is the model number for the Microsoft keyboard with fingerprint reader?
2. What happens when you try to use the fingerprint reader?
3. Have you upgraded to Windows 8? Was it working fine with your previous operating system?
Jan 22, 2019 How to connect a Microsoft Bluetooth keyboard to your device. To connect your new Modern Keyboard with Fingerprint ID (EKZ-00001) or Microsoft Surface Keyboard use these steps. Connect the USB cable to connect the keyboard with your computer. Turn on the keyboard using the sliding button located on the side of the number pad.
I would suggest you to check with the full name on Windows 8 compatibility center to see whether the device is compatible or not. You may refer the article:
Windows compatibility center
You may search the name or if you find that the keyboard that is listed is the one that you are working with, you may reply back to us.
Surface Keyboard With Fingerprint Reader
Hope this information helps. Please reply with more information regarding the issue so that we could help you further.