Convertible boot fitment

I've ordered a boot from Legendary interiors. The flaps do not come down to catch the snaps on my rear door panels. They suggest that factory panels didnt have those snaps.

I have included a third pic showing my current boot, although worn and old, still fitting far better than the proposed new boot form Legendary.

Please let me know if the flaps are supposed to come down and catch a lower snap on the door panel or if it is an aftermarket addition.

Thanks!