You should receive your luggage tags in the mail at home prior to your trip. You'll need to have any luggage that you're checking with them pre-tagged.
As far as where to go at FLL, you'll go into the same doors at arrivals exit where you leave the terminal at your flight arrival. There will be a clearly marked kiosk where you'll be able to check in for your DCL transportation. Whether you're arriving that day via flight or just going to the airport to use the DCL transportation, it's the same spot.
Then you just hang out in that area until the busses start picking people up, which I believe is around 10 a.m.?
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