The oddball "support" is for the base of the lift.
Based on what was just said, looking at the "support" piece, it makes sense. The stair supports are set out farther and angled to be flat as the "support" sits at roughly 45 degree. Also, the 2 flat connections will hold the initial lift track (once again, based on the angle of the curve between them). The 4 connectors on the large end will bolt into a footer or some other form of support that is in the ground for stability, and the top section has the + on the end to bolt directly up to a piece of trussed lift track. Look at the pic of the crazy red support and think of what I just said while piecing it together...you will then see.
The lift stairs are also oriented correctly in relation to the lift (AKA they are on the correct side).