If you look a little, I think you'll find that the Sinar plate simulates a shutter of the right size for the lens. It has a tube threaded to accept the lens cells' andis the right length to give correct spacing. It has no diaphragm.
The cells should unscrew from the tube. If you want to use the lens, you'll have to put the cells in the correct shutter or barrel.
It isn't clear that you'll be able to use the lens as you want without additional work and expense.