MR816 - headphone routing???

How in the world can I route a cue-mix to one of the headphone outputs
on the MR816 in cubase 10.5?
The manual of the MR816 is not helping, the descriptions don’t match the
current cubase. I’m tearing my hair in despair, having spent numerous hours
trying to find out! Help would be much appreciated.

Select the headphone chanel of your MR816 as output bus for thr deired Cue Mix in Cubase. If the MR 816 Headphone output is is not a discrete output, use the MR 816 software to route the desired channel to your headphone output.

Thank you, I will try to do that. But what do you mean by “MR816 software”? And where on the computer (mac) can I find it?

The software is called MR editor, but since I neither am I using a Mac, nor the MR 816, I can´t tell you where to find it. What I do know is, the MR816 comes with a manual, and if it doesn´t, it can be found online. Maybe time for you to start reading it?