as far as I can remember, you had to install the rotor on the adapter,
then install them on the hub, along with a supplied washer.
sounds kind of backwards, to me, I'd put the adapter on the hub,
and then you have the leverage of the wheel to get the disc mounting bolts tight enough.
though once tight on the adapter , disc+adapter can be removed
and adjusted in location, if needed, with the aforementioned washer.