If you opt for an offer with shuttle service from the terminal, a bus from the operator will take you to your rental location just outside the airport. 

The buses usually leave the car park near the terminal every 10 or 15 minutes during the location's opening hours and regularly take no longer than 15 minutes to get to the location.

However, the buses may operate as an on-demand service. You will find the information on your voucher. The exact location of your bus is usually on the voucher. Most of the time, the buses are clearly marked.