Install the apps on your computer:
Logitech Unifying Software – Logitech Support + Download
1- Turn off and disconnect all other Bluetooth devices from your laptop.
2- Plug in the unifying receiver you would like to configure
2- Open the Unifying Software app, go next
4- Turn on the device you like to pair
5- For keyboard, test typing.
6- For a mouse tick Yes, then next
7- Choose between Finish or Pair another device (repeat the process until you've added all the devices you want)