These drivers work as recommended by Cisco: USB to UART Bridge VCP Drivers Silicon Labs. How to use the IR829/809 Mini-USB Console Cable with Windows 10.
The way to tell the installation of the Cisco USB driver is good and the connection is good is as follows: Open the Windows Device Manager, navigate to the Ports (COM & LPT) section and open the section so you can view the indivicual Ports, plug the cable into the PC and the Cisco router and you'll see a new port appear, typically COM4 which is the default as setup by the Cisco USB Console driver. If you unplug the cable, the port will no longer be listed, plug it back in, and it will be listed.
The response time between connecting the cable and seeing the result in Device Manager is the USB Serial Port driver doesn't work. In theory Win 8. Intel Dh67bl Drivers For Windows 10. x and Win 10 should be close to Win 7 (this is the reason why Microsoft is confident enough to encourage Win 7 and Win 8 users to perform an in-place upgrade to Win 10 for free, if it's not highly compatible, Microsoft will be tortured by support requests / complaints).
With that said, the difficulty you're experiencing may be different than what I encountered. I wish I had experience with Windows 8.1, but my limited experience has been with Windows 10 as part of the preview program. Broadcom Bluetooth Driver Windows 10 Lenovo here. I would perform a test of the Cisco package on Windows 10 but Win 10 was erased from the computer was using in the lab a week ago (so the computer could be used by another staff member and the Microsoft Win 10 preview program has ended now that it's in production, thus I don't have a reference Win 10 platform currently).