All the manual has to say is this:
Door Adjustment — Rear
Loosen the rear door hinge-to-rear door bolts until the rear door is able to move slightly.
Align the rear door.
Align the rear door body angles to the rear quarter panel.
Be sure that the rear door is flush to the body.
Tighten the rear door hinge-to-rear door bolts.
Tighten to 30 Nm (22 lb-ft).
Loosen the rear door striker bolts until the striker is able to move slightly.
Align the rear door striker to the rear door.
Tighten the striker bolts.
Tighten to 22 Nm (16 lb-ft).
Adjust the front door. For additional information, refer to Door Adjustment — Front in this section.
https://secure.revolutionparts.com/levittown-ford/auto-parts/2016/ford/taurus/sho-trim/3-5l-v6-gas-engine/body-cat/rear-door-scat
Part 16 is the striker, 17 is the striker screw -W710993-S901