Using A4's inputs via USB

Hey, I’m new to the A4 and I use it within Ableton via Overbridge.
How can I route an audiosignal from Ableton to e.g. track 2 of A4 to apply filters on the signal?

I tried in Ableton “Audio to” and below this field there is only the option “Track in” wich is not the function I search for.
In overbridge I tried to enable master inputs as well as track 2 inputs. But I don’t understand how to bring the signal to A4.

Or do I need to plugin audiocables?