Can the additional drivers unlock and lock the car with their phone?
The car is locked/unlocked with a virtual key that is downloaded on the main driver's phone.
Just like a real key, this virtual key can be used by only one person at a time.
Additional drivers can of course request the virtual key to be transferred to their phone at any time.
Please note that, while it is not necessary to have internet to connect to the car, it is required to request the transfer of the virtual key to your phone.