This is talking about ventilation and how important it is
https://www.backyardchickens.com/articles/chicken-coop-ventilation-go-out-there-and-cut-more-holes-in-your-coop.47774/
Then build a wide ramp and put something on the ramp to give them traction. With the coop sitting that far off the ground you'd have to cover the sides of the ramp so they don't fall off or jump off and injure their legs.