I bought a Logitech K380 for use with my phones and new tablet. It’s manual is here, and it connects to the tablet with a US keyboard configuration. This can be reconfigured using the Android setup bluetooth screens. …
To pair/connect, press one of the yellow buttons until the white light flickers, make the client issue a bluetooth scan, select the K380 and you will be issued with a 6 digit challenge, when typed into the keyboard the pairing is made.
To connect tap the paired channel button, the light pulses; if paired this is what you need.