I used both 3.0.2 and 3.1.1 and got the same error on both.
I did seem to have missed some step from the instruction you linked, namely deactivating the other VR plugins.
I"ll go over it once more and see if it fixes the issue.
@Tony PH Lin
There is a bug in a clean install of the UE4 plugin.
I get this error non-stop: WVRSimulator: Error: Failed to load Simulator library.
This prevents me from packaging or launching the game
@Tony PH Lin @Cotta