I do not beleive that connectior is a four way connector usable for castle pieces.
It looks like it is not tall enough for it,
But I do not have the set, I cannot say for sure.
I believe that four way connector is for the bottom of the house, the wood foundation.
Which I know is only half the size of a regular steck castle piece.
Unless there is another four way connector in that set that is taller?