The best way to mount a post is still to make the post longer and core drill for the post, reinforce the ID of the post with a 19" long reinforcing bar and set the post in the core drilled hole with a commonly available grout. The Wagner Companies carries the Rockite (for interior installs) or Kwixset (for exterior installs) brands from Hartline Products.
If you are using the SA550 wedge base with stud, you slide the cover flange over the post to get out of the way. You would then insert the SA550 inside your post. Then tighten the nut on the bottom to expand the insert to lock in place. The threaded rod on the bottom is then set into your concrete or, in the case of an existing concrete slab, you would need to core drill for the threaded rod and set it with the appropriate Hartline Product listed above. The threaded rod is to give you an uneven surface that will help hold the threaded rod in the concrete. You do not want a smooth surface that could readily pull out. Please note, the nut you tightened to expand the SA550 will also have to be recessed into the concrete. It cannot be exposed above the concrete or the mount will be weakened. Once the post has been positioned, you can then slide the cover flange down to finish.