Okay, so this is just for the night? They free-range out of there during the day year-around?
And from the picture you have 3 chickens?
Try using the hutch-style "coop" as the nesting boxes, put a thick layer of straw on the floor near the door (see pic), and put a piece of 2x4 as a roost - chickens like to sleep higher than the nest boxes. Maybe one end from the left corner of the wall, to the top off the coop/hutch on the left.
Make sure they have access to fresh water during the day (you only need one container probably), and food.
See attached pic.
(I appreciate this looks a lot more like
lalalandchickens 's post than I intended!

)