I thought you needed to get the shuttle to Citywalk then pick up the shuttle there for Cabana bay.
This is from touringplans
Super Star Shuttle
Universal offers free scheduled transportation to SeaWorld, Wet 'n Wild, and Aquatica for its on-site hotel guests via the Super Star Shuttle. Departure and return times are limited, and based on regular park operating hours; typically there are up to a half-dozen trips each way to SeaWorld, and only a couple in either direction to the water parks, but during slow season there may be only a single trip scheduled each way. Boarding passes are required and available at the ticket desk in each hotel lobby, between one day in advance and 30 minutes prior to departure. The Super Star Shuttle picks up guests directly at Universal's three luxury hotels; guests at Cabana Bay must transfer to the parking hub and catch the shuttle there.