From our experience with them, they provide ground transportation from the nearest major airport to the cruise port. In your case, the Miami airport would be the closest, so ground transportation is probably only provided from/to there.
But I've also found the ground transportation to be quite expensive, especially if you have a large party. If you have an entire family, it may be cheaper to rent a car for the cruise duration at Fort Lauderdale, drive to the port, leave your car at the port, pay the daily parking fee and then return the car to Fort Lauderdale when done. Just a thought. We've done it both ways (renting versus taking the Disney bus), and in our case renting and leaving the car at the port all week was less expensive. Combine that with a cheaper flight, and you can really save some $$$.
