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Its really hard to tell from those pictures to be honest. The orange component needs to be pushed in to allow the shaft to be installed flush with the back of the disc, the hole down the centre of the piston will need to be clear of burrs to allow the spring to work correctly. When assembled the mechanism should be super smooth and require very little force to make it move, if its tight try loosening the bolts and or sanding the piston/piston cover mating faces, a little lubrication will help a lot. Clearly you need to put the bearings in x6 :).
Did you see the video with the exploded animation, this might help you, you could also try printing out the drawings and laying the components on the drawing?
Hope this helps, thanks Dan