Step 10 is to install the zipper.
I previously mentioned marking the zipper fold line on the wrong side of the lining assembly:
I used that line to fold the top town towards the right side of the lining assembly, pinned in place, and stem pressed this fold:
I noticed - and checked - that the pocket is not exactly parallel to the top and bottom edges of the lining piece. Too late to change it now. Important to me is that there is enough clearance for the lower corner seams. Besides, the lining will be hidden inside the purse, so who's going to know, right?
For each side of the zipper, I fit the zipper into the fold as instructed ...
... then I pinned the fold tightly over the zipper, pinned it in place, and stitched as directed:
After another fold and press, I topstitched along the zipper on each piece:
Step 11 is to attach the lining to the top of the bag - and maybe more!