Added
Once a card is active in the system, you link it to an employee. You can do this two ways — via the employee or via the card. Both reach the same result.
Open Administration → Access cards and stay on the By employee tab.
You can reach the same result from the By card tab: edit the card in the list (inline) and attach an employee to it.
A client can have multiple devices. A single card doesn't have to be active or assigned on every device at once — you choose which devices the card is valid on.
Because of this, the system can also be used for physical access control: the device works with electric locks, so you can control exactly who may pass through which door.