Should installing the driver manually not work via this method here, please try using the zadig utility described below.
Select All Devices
Open Up the Zadig Utility and make sure 'list all devices' are selected under options.
Find the Flirc Device (Interface 1) or the bootldr in the dropdown. Also, make sure libusbK is selected in the list as shown by the yellow arrow.0
Same image as above demonstrating the bootloader
Install The Driver
Then click Install/Reinstall Driver
Optional (Verify Installation)
Flirc is now installed, you can double check Device manager.