If I assign the track output to output 3-4 in Logic Pro X, I get a nice line level out of output 3-4 [Edit from me, Clas; I think he actually here mean the ports that on the back of the hardware UR44 are labeled 1-2] from the Steinberg UR44 which is sweet for isolating lets say a drummer track.
The UR44 is a 4 in and 4 out interface. He already is using out 1/2 for his monitoring and he has routed 3/4 successfully as a separate out. So that’s both stereo pairs routed independently…you could also route 3&4 as 2 mono signals rather than stereo.
That’s independent routing…there is no way you can route 6 channels independently on a 4 channel interface. The Additional outs are there because 1/2 and the main Stereo out both have Mix1 always going through them (Not sure what use the extra set are to the majority of people tbh)
I doubt that the guy has the numbering wrong …probably logic is interpreting 1/2 as Line outs 1/2, 3/4 as 3/4 and 5/6 as the main stereo out.