I don't know what Traktion is, I suspect it's your recording software. I also assume your keyboard produces sounds and is not just a MIDI controller.
Connect your Keyboard's MIDI out to the Aard MIDI in. Connect the Aard MIDI out to the keyboard MIDI in. Connect your Keyboard's audio output(s) to the Aard.
Create two tracks, one MIDI, one audio. Arm both tracks. Press record and play your keyboard. When you're done hit stop. Make sure the output of the MIDI track is routed back to the keyboard. When you hit play the MIDI notes are sent to the keyboard and play back what you just recorded. You can choose a different instrument on your keyboard as well; maybe the part you recorded sounds better as a string part than a piano part, yada yada. You could also send the output of the MIDI track to some external sound module, a diffferent keyboard, or an internal soft synth.
The audio track you created should contain a waveform of what you played.