You need to slip the deluxe interior door handle through the opening, then lift a bit so the top can hook over the top of the door frame, then pivot down to the vertical position. Then it should just be a matter of installing all the pins and screws + door pull.
If it is sliding upwards, there must be something in the way or the top of the panel is bent or something.
Should hook and literally drop into place.
I know another member had similar issues (and a thread) about a year ago. He resolved it, but I don't remember what he said was the problem. Maybe try a search?
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold