Not exactly sure how it is handled in the Miami Port now, it's been awhile since we cruised from there but the way other ports handle it, if you have a pre arranged time for pickup with a Lyft/Uber driver you wait in a different area outside and never get in those Lyft/Uber or Taxi Lines.
Bayonne Port had it signed very well for prearranged pick ups for Uber and Lyft.
Maybe others today with prearranged pick ups through Uber and Lyft can chime in better for Miami.