Car rentals have offices in the terminal which are usually open from 8.00 until 23.00.
Other questions on the same topic
Where can I leave my car keys if the car rental office is closed?The offices are equipped with key drop-off counters even at closing times. Some Airlines are even equipped with key drop-off boxes in the parkings.
Where are car rentals located?
The car rental offices are located on the ground floor of the Terminal