Add M3 nuts to the base.  Mount the base to the wall, then screw the “Back Plate” to the base with 4 M3 countersunk screws.  Place the tablet into the cradle.  Finally, add the “Top Trim” and secure with 4 M3 screws on the top and bottom.

Use M3 countersunk hardware to assemble it.

These screws worked well for me.