Alamo rental-shuttle from Miami port to MIA

New to cruising and first time renting a car not immediately after getting off plane...

What can I expect when picking up the Alamo shuttle from the port of Miami after disembarking the Horizon?

Is the shuttle spot clearly marked? How far away from the luggage pickup area? Is it a bus or a van? Do I tip the driver? How long is the typical wait? How long is the trip? What questions did I miss? Lol

TiA

Shuttles ride between each terminal at the Port Of Miami and pick up passengers for the short fifteen minute ride back to the Miami International Airport Rental Car Center which is located directly across from Miami International Airport.The shuttles normally leave for the Rental Car Center when they have a full load of cruise passengers. The shuttle drivers will normally ask to see your car rental reservation before they allow you to get on the shuttle. Alamo and National which are owned by the same company share their shuttles.I normally tip the driver when they help me with my luggage.