Promised was a pickup in Miami near the Bayside Market or Miami Beach (Collins Ave). However, this did not take place without replacement, so that I had to pay the cab to Fort Lauderdale out of my own pocket, for which the customer service has not apologized.
Also, the departure and return times were not correctly specified, whereby I had to look for these on the page of Balaerian Caribbean itself.
The departure times were changed: Departure is now 10 a.m. and return was at 6 p.m. (I had to ask on board).
You can also book the tickets directly on the site of the ferry operator, here is also more flexible so that you can also plan overnight stays, which I would also recommend.
The trip with the ferry and the island itself and the possibilities that offers that is really great.
I enjoyed the almost 6h very much and the island can be explored almost completely in the time (there are golf carts for rent for a fee).
The crossing was manageable with just under 2h, whereby you can also go on deck and marvel at the infinite sea blue.