Yeah bro, those are the brackets. I didn't see any extra instructions but that doesn't mean they weren't there tho.
I didn't see your reply before the action though. We ended up trimming some metal from the bumper, basically on the part of the bumper with the captured nuts. We cut length wise under the three captured nuts and didn't cut the frame at all.
The bumper bolts to the bracket and sits on top of the frame. I think I'm gonna make up a bracket to run from the spot on the frame where the 3rd stock mounting hole is, up above the top of the frame and bolt through it into the 3rd captured nut. Maybe even weld along the seam between the bumper "tab" and the frame on each side, I haven't decided yet.