You can pair a Bluetooth keyboard with your system as follows:

BT-KEY3XL:

This Full-size keyboard can connect by Bluetooth, or USB cable included in the package.  

1.  Enable Bluetooth to search on your phone, tablet or computer.
2.  Open the keyboard and press Fn + 1 for Blue tooth mode.  
3.  Press FN + C to enter Blue tooth pairing mode. The middle blue LED ‘State’ will flash when the keyboard is in discoverable mode. 
4.  Click or tap “Plugable Folding Keyboard” in your device's Bluetooth settings. 
5.  Press Fn + Q, W, or E to set the compatibility mode.

BT-KEY3:

1.  Enable Bluetooth to search on your phone, tablet or computer.
2.  Press FN + C to enter Blue tooth pairing mode. The blue LED will flash when the keyboard is in discoverable mode. 
3. Click or tap “Plugable Folding Keyboard” in your device's Bluetooth settings. 
4. Press Fn + Q, W, or E to set the compatibility mode.