The two files are for the top and bottom of the ball screw mounts.
Top Mount: make sure side piece is faced down to connect to the side extrusion. I used some washers and t-nuts to mount them to the extrusion. The top block should sit perfectly on the mounts if your ball screw is tall enough. I used M5 screws to connect the block to the mount and M4 screws for the side extrusion.
Bottom mount: I installed this first. it should slide over the bottom block like a sleeve. you will need long M5 screws to secure it to the block. I always use washer when securing. The top part of the mount that you secure to the extrusion is open so you can adjust to how you like. I used M4 screws and t-nuts for this.
Before doing a final tightening of all your screws make sure everything is aligned to your needs.