Select generic controller on the input menu and you should see your MIDI device listed. You may need to get an adapter available from music stores (they usually connect to the joystick input on your soundcard). Plug the cable from the midi out of the keyboards to the midi input of the PC or soundcard.
Let’s look at how to connect a Midi Keyboard to FL Studio: One of the first things to upgrade in your FL Studio setup, is usually a midi controller.