Hub rings can come direct from Baer. They are the same they use on their track kit.
Did you follow these steps?
The smaller threaded holes are what mate up to the knuckle. The bracket goes behind the tabs of the knuckle that the original caliper bolted to. Run the bolts from the outside through the knuckle tabs and into the threaded holes of the bracket. Not that there will be a little grinding required on the top of the knuckle for clearance to the bracket. Don't go crazy, it shouldn't take much.
The bosses on the bracket should extend outward, away from the center of the car, and the narrow end of the bracket should be higher than the wide end.
Put the rotor on (after drilling for 4x108, and using a centering ring) and then put the caliper on. The caliper should fit to the outboard side of the large bosses, and the bolts should be run in from the backside, through the bracket, and into the threaded holes on the caliper.