How do I connect omega c-67 enlarger to baseboard?

Hi! I have been scanning these forums for this and I have come up short.
I have a baseboard, all screws/ pegs to it, the full enlarger with lighthouse but I can’t seem to tell if I am missing a piece for it to attach to baseboard. Attached as some images, does anyone have a spec sheet or a how-to I stalled these two pieces? I found a random piece in the darkroom box I got from a friend and am not sure if this even goes to it.

Welcome to Photrio.
If you can't get direct help here, this is a link to KHB's page on their website for that model, which includes a lot of information as well as a link to the reprinted instruction manual that they sell: http://www.khbphotografix.com/omega/Enlargers/C67.htm
Their manuals are very high quality, and they themselves are a good source of information in general.

To get that "U" piece back into the column, it looks like you feed the two long protrusions of the "U" shaped bracket into the two larger holes on the column, then slide it back to engage to two small holes.