I JUST installed the game fresh… Launched it, and when the opening video finished, it presented me with a license agreement dialog, but I could not click on the buttons.
After some fiddling, it turns out that there was some kind of mismatch between the pointer display location and the place the pointer was being registered. (but only in the x-coordinate!)
By swiping the mouse around, I found that with the pointer all the way at the right side of the screen (but still vertically in line with the buttons), I could activate the “hover over” effect on the buttons, and thus click them, even though my mouse pointer was nowhere near the buttons - way over to the right.
I used this method to go into settings, and change the screen setup to “windowed fullscreen” which forced the resolution to native 3840x2160 4k… and now the mouse registers in the correct place.