If I understand the device think of the USB as emulating 2 connections
1 - Power, same as the 5volts.
2 - Ethernet (LAN over USB)
1 is wired on one side, wireless on the other. Similar to connecting an Ethernet form your PC at the LAN of an AR150
2 is like connecting power to an AR150 and running wireless on both sides.
3 is like connecting power to an AR150 as a mesh node