Hi, I really don’t know what the transfer relates to. It is not normal, for most travelers.
But are you staying at a hotel in Jamaica? I can only think that maybe the transfer is like the taxi to get you from your hotel or accommodations in Jamaica to the airport. So you would take the taxi going to the airport and then picking you up at the airport. Could this be it? Or else I have never heard of a transfer to be paid to get to Cuba. It might really be something specific to Jamaica and not to Cuba.
Take care,
Mario.