Since it is an oversized item, you'll be picking up the keyboard from the side of the baggage claim area that is closest to the tram to the rental car shuttle -- at least that is my recollection of where Delta's oversized item pickup is. Consequently, you'll only have to roll the case a short distance to right outside the terminal building and onto the tram's elevator, then from the tram to the rental car itself.

Is there a distance limit to how far you're able to roll the case yourself?