Change origin of object

Apologies for what I am certain is my error, newbie. I am trying to follow the tutorial below and am unable to get the snapping to vertex working. Running 2.82a macOS.

I’m in object mode, top view, Origins is selected in Options, axes appear and move when using G. But they will not snap to vertex regardless of whether I use CTRL or not. I have snap to closest vertex selected and snap magnet is blue. I’m at 1:05 in the video. Losing my mind over this.

THANKS

No idea. Never did it that way.

Go into edit mode, select 1 vertex, shift + s , “cursor to selected”.
Go into object mode, right click, “set origin”, “origin to 3d cursor”.
Done.