> I got the UCX running via USB already, will I need to change any specific setting at the device to run it as a master?
See RME driver settings dialog and RME handbook
> How do I connect it via ADAT
With a an optical cable (TOSLINK) which can usually be up to 15m long. The ones from Mutec are ok IMHO.
> what does 'Steadylock is superior' mean?
Do you know "google search" or did you every read your devices handbook ?
> I also am not really able to follow you on this one, is that a software mixer related task?
Yes you need to configure the Motu to route i.e. its 8 analog inputs (or Mic Pres or whatever) to the ADAT out channel.
The ADAT OUT Channel of the MOTU is connected to the ADAT IN channel of your RME device.
There you see then the audio signals coming in as ADAT inputs ...
> does this mean I will not need to install the motu drivers?
I don't know how Motu packages their software.
RME driver installation also installs TM FX the routing software.
But I am pretty sure you have also the Handbook of the Motu available to read on your own, how software usually is being installed on the MOTU. If there is only the driver, then it should be clear that their routing software is included.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13