Difficult to tell but to me it looks like you went through the whole subframe. I'm not 100% sure on that brace itself but looks like it mounts just like a recent one I did.
That nut I believe goes inside the subframe.
https://youtu.be/8pVPPgYLxQk. Heres my video,go to the 2 minute mark to see what I'm talking about. Hope that helps.