Nikon Z UniWb profile

Heya.

Coming from Canon, where stuff was easy, I am clueless about setting of the proper WB for UniWB on Nikon.
Dark image measurement failed, white image measurement failed, monitor magenta color shot failed. The camera refuses.
Is there any known way to set UniWB for Nikon Z (5?).
Thank you.

Have you tried
blog.kasson.com/using-in-caera-histograms-for-ettr/preparing-for-monitor-based-uniwb/ + blog.kasson.com/using-in-caera-histograms-for-ettr/8-a-one-step-uniwb-procedure/

That's fugly long. Will try in the next round of fiddling with stuff. Thank you.