What do you mean by RVO mesh?
No movement scripts except AILerp has support for 2D at the moment, and since AILerp is intended to follow paths exactly it cannot use RVO, so currently no movement scripts have support for RVO in 2D. The way you would use it would simply be to set the RVOController.movementMode to XY instead of XZ. The gizmo will change to a circle in the 2D plane to reflect this. Then in the movement script you would call rvoController.SetTarget(whereIWantToMoveTo, desiredSpeed, maxSpeed) to set the desired target point and finally you would get the processed velocity using rvoController.CalculateMovementDelta(Time.deltaTime);
So something like
rvoController.SetTarget(transform.position + Vector3.up, 1, 1);
transform.position += rvoController.CalculateMovementDelta(Time.deltaTime);