The best adhesive to use on a car door panel is non sag door skin adhesive from sem according to popular mechanics.
Glue on door panels.
Panel bonding adhesive has excellent adhesion to a wide variety of plastic and metal substrates.
We have commonly seen panel bonding kits used to bond door skins roof skins quarter panels and truck bed sides in place.
Minor fixes may get by on cheap glue but real repairs require reliable strength.
Containers of this adhesive can cost up to 65.
Purchase a decent applicator gun to complete the job.