Hey Morten, Math > Absolute hasn’t changed.
I was lazy and just downloaded the zip file and loaded it up in 2.83 and it worked.
As for the Absolute, the only place he used that is in the ‘Symmetry’ those separate xyz and combine xyz with the adsolute nodes in between can now be exchanged for one node: the Vector Math > Absolute.
At what point in the video do problems start for you?