Free airport shuttle was a fiasco. Must call and reserve the shuttle before travel altogether. Arriving to the airport and calling does not work. First, if you do not have a German eSim or international roaming you won’t be able to call at all. Second, even if you call, unless you reserved the shuttle in advance of travel (like back when you were home), you cannot get the shuttle. When you make a reservation for the shuttle it is for a specific time, so if your plane is late, no shuttle for you. For some reason, the frustration this causes is lost on the hotel staff.