Whitelist is used to specify the computers which should pass through the software without authentication.
Such computers are not listed at the Devices page, and their usage is not tracked.
The whitelist can be used, for example, to let your IP cameras communicate without login procedure.
You can also whitelist some of the computers which should be accessed remotely.
Bandwidth Manager uses IP whitelist and MAC whitelist to define which computers are allowed to pass-through without authentication.