An email and an SMS with further instructions on how to access the lock will be received by the person who is authorised for access.
They need to click on the link and enter the PIN code on the next screen.
They will then be presented the option of locking/unlocking the door.
Press the 'Activate Lock' button, there is no need for the to hold the phone to the lock.
They will have also received an email as per the below. This can be used if they haven't received the SMS or if there is an issue with phone signal. They aren't required to do both, either/or will work as they both activate the lock in the same way.