This bracket gets a bolt with a hole in the head so it can be wired, because you don't make this too tight. The idea is the bolt will slide out of the slot if there is aft pressure put on the wing.
These little platenuts are for an AN4 bolt. The big washer lays on the bracket just right. I decided to use the washer as a drill guide and to drill this 1/4 from the get go. I considered starting with a small drill but chances of getting it centered are low.
So I clamped the washer to the two brackets and clamped the two brackets together and used my angle drill with 1/4 bit to drill thru the hole. Worked great.