What is the best way to to install an exterior door on a slab between a round wooden pole and a wall 4 feet away. Pole is about 9-inch diameter. Ceiling height 8 feet. Wall is block up to 4 ft.and is perpendicular to the door. Rest of wall is wood.

I would nail a 2x6 to both the pole and the block wall. Install a header 1'4" higher than the door frame height, this will be easier if the door is prehung, is it? You will need to add two more verticle 2x4 or 2x6s just outside the door frame that tie to the first two 2x6s. Do you need/want a threshold?

I think a pic of this door would help if you have one