Here is the driver: https://sfo3.digitaloceanspaces.com/drivers/1800%20Driver%2011/26.exe
The most up-to-date drivers can be found on JD's website: https://www.jamesdonkey.com/software.html (download the driver that has RS2 in the name)
NOTE: if you have a pre-existing install of the drivers you may need to uninstall it before installing the new ones.
If you cannot use the latest driver, you will have to upgrade your keyboard firmware. Use this software to upgrade your keyboard: https://drivers.sfo3.digitaloceanspaces.com/1800%20Firmware%20update.20.exe
James Donkey Software URL: https://www.jamesdonkey.com/jamesdonkey_software.html
Select English on the top.
FN+4 press for 4 Seconds and enter 2.4G Pairing mode, use this only if your receiver is not working.
FN+1 press for 6 Seconds to Enter Bluetooth Pair Mode.
FN+1, FN+2, FN+3 to switch stored Bluetooth devices.