This guide explain how to control a skeletal rigs from an OptiTrack in Notch. See also the Notch manual for more information.
Import the skeleton into Notch. When prompt, make sure to change the Scene Scale to 0.01 and disable Convert Axes (FBX).
Add the Skeleton in the Nodegraph. Make sure to have the Skeleton facing the Z (blue) axis.
Add the OptiTrack Mocap Skeleton node in the Nodegraph and enable Rotate Bind Pose Joints. Change the Input Skeleton Scale to 1.0. If needed enable Mirrored.
In the Nodegraph the setup should look like in the image below. Is important to change to Skeleton Coordinates in Motive to Global, otherwise the avatar will look distorted.