You can expect your driver to await you for one hour after your flight lands. He or she may make enquiries with the airline, customs, or immigration if you have not appeared within an hour, and will leave the airport if there is no sign of your party.
In order to make your transfer go as smoothly as possible, call your supplier if you are running late. Contact details are listed on the voucher you received after booking your transfer. If you expect to take more or less time than usual, notify the supplier at the time of booking!