Motion Caption Rig data as state estimation on device (for autopilot and control)

Hi guys - I’ve asked this in the emlid forum aswell a couple of days ago without a response, but I feel it might be better asking it here!

Some facts:
Raspberry 3 + Navio2
Arducopter: 3.6
ROS: 1.12.14 (Kintetic - Emlid Version 20190227)
QGroundcontrol on Mac
Vehicle: Quadrotor

I have a node from an external state estimation (Qualisys), that provides accurate data via ROS. I want to feed this data to the Navio/RPi for the autopilot and control system.
Sounds pretty simple and I thought I can just subscribe the state estimation node to a certain topic. Unfortunately I’m pretty new to all this stuff and am not at all from an IT background so I’d like to ask for some thoughts of the pros over here.

Any hints how to solve this problem, that a programming newcomer could understand?

I am able to listen to the data on the RPi itself and I followed the instruction for the Opti track system, that are give here in the Docs. Now I’m a bit stuck…

Some hints are highly appreciated! Thank you!