It was so useful! Thanks!
But it took me two attempts before I understood the second step (tap the 4 digits PIN code previously entered on the computer) BEFORE the connecting attempt by the computer is done.
So in case some made the same mistake as me:
Step 1: (On your computer) tape in your 4 digits PIN of your choice. Press connect
Step 2: (On your Bluetooth keyboard) While the computer is attempting a connection, quickly type the same 4 digits PIN then press ENTER.
Step 3: Watch your computer finally connecting to your Bluetooth keyboard. At last.