I'm running a later version, but the idea should be the same.
Mate the PLANES of each so the middle of the tube and middle of flat piece align. Might be different planes and you may have to flip orientation.
This is assuming the cut tube is centered about the origin and the cut is symmetric about any plane.
Once that is done, I assume you can pick the face of the flat piece and the inner EDGE of the cut tube and designate your 2mm.
The last, or first, would be to mate the front of each as you wish.