You have to add any additional drivers to the booking before they can legally drive your rental car.
The additional driver must go with the main driver to pick up the rental car and present a driver's license that they've held for a minimum of two years.
Adding a driver after pick-up
If the additional driver cannot be present at pick-up, they can add themselves later during the trip. They will need to go back to the car rental counter with the primary driver. However, until they are officially added to the booking, they are not permitted to drive the rental car.