SETUP
You can setup the NAS either through an explorer window or through Qfinder (which is what we did). For that you should head over to the official support page to download the latest program version.
Through the Qfinder application not only can you find the IP of the NAS but you can also download the latest firmware and start the setup procedure (you will need to choose between quick or manual setup).
You can also setup the preferred RAID mode for the installed drives or leave it for later on (here you can see that we indeed used 6 Enterprise Capacity V3 4TB HDDs by Seagate).
After you are done with all the settings the process takes less than 5 minutes to complete.