They are totally separate lanes - the fast track card refers to dedicated immigration desks staffed with immigration officers where you need to present the card to be eligible to queue/access those desks, whereas the smart gates at immigration are automatic gates on either side of the hall with only one officer there to register anyone who is unregistered or has a problem. Sometimes there is no one at all, but not a problem if you are registered of course. The smart gates accept UAE ID card, e-gate or machine readable passport from the valid countries.