In addition to the manual, we have this article ithat may help in your case:
Can NetWorx monitor all my devices (iPad, laptops, smart TV)?
Basically if your devices are not Windows-based computers, then you will be only monitoring combined usage without per-device breakdown, and only if the router supports the necessary SNMP or UPnP functions.
Unfortunately there is no simple way to monitor every device in a home network as they access the Internet independently through the router, and there is no way to capture their usage from a regular computer connected to the same network.