Auto rudder doesn’t keep you on the runway.
Auto Rudder is used when you don’t have rudder pedals.
It coordinates the ailerons with the rudder, so if you bank the aircraft, the rudder moves appropriately.
Likewise with steering, you can use the ailerons to steer on the ground if you don’t have rudder pedals.
If you are looking for a function to help steer the aircraft during these phases, that would be in “Assistance Options”, “Piloting” either “Assisted Landing” and/or “Assisted Takeoff”.
I don’t believe either of these has a key assignable function, they must be selected from the menu.
While in the sim, you can turn over control to the “AI Pilot” and let them do it, however, I’m not sure how well that works. That can be turned on from flight assistance button in the on screen toolbar.