You don't need those. You need this: https://www.wickes.co.uk/Youngman-Aluminium-Ladder-Stay/p/530039.
That's what I thought at first, but my standoff moves the ladder too far away from the wall lower down so I can't reach it. If you look at your image and continue down below where it says "Tap to zoom" you can see how far the ladder is from the wall.