The Ring lamps are slightly smaller diameter than the original foglamps.
Once the original lamps are removed, the "grille" bumper insert that they fit into has a ledge below the lamp. This needed to be about 12mm higher I think. (Should have made step-by-step notes) I found a piece of plywood about the right thickness and cut a piece the right shape and fixed it using the original foglamp screw, plus another. The the Ring lamp bracket screwed to this new base. Only "damage" is an extra hole in the mounting and that is inside the bumper, so invisible. Can easily be put back to standard.
The original mounting has plastic lugs to mount the lamps at the sides. These do get in the way of the Ring mounting screws, making them a real pain to tighten, but otherwise a straightforward job.
Drag a lamp out and have a look. Ask again if all is not clear. The original is held in by the two hex screws you can see at the front, plus two screws under the bumper. Then the whole thing has to tilt out at the top, with a bit of levering to ease the bumper aperture. Some special language may be necessary for a few moments.