I haven't experienced this need to be exactly right with measurements myself.
Note that the description is wrong. It's not a maximum of 20 lbs, it's just that the counterbalance is weighted for 20lbs. If you have 20 lbs worth of tabletop on top of it, there's basically no effort required to lift the table. I'm not sure what the maximum would be, but I was not concerned about my 45 pound monitor at all.
Basically all I did was screw a couple of boards to the top of the frame, and then C-clamped the bottom of the frame to a desk. I was always planning on doing it "properly", but never got around to it.
Is it really that hard to grasp? Get a drafting chair. Or close the browser tab.
I leave the keyboard, mouse and power adapter on the standing side, as motivation to spend less time sitting. So far I can manage alternate hours sitting and standing, which isn't too shabby considering how out of shape I am.