If you can smell amonia, or see condensation/frost on the wall, you don't have enough ventilation.
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First I think you need to figure out the REASON (or explain it to us) you want chickens?
I'm usually the oddball when it comes to space ... the "standard byc" answer is 4 sq ft per bird in the coop, plus 10 sq ft per bird in the run ... I think much bigger is, much better!

I like to see 6-10 sq ft per bird in the coop, PLUS 100+ sq ft in the run for EACH bird!

and still you will have mostly bare dirt in six months!
However ... there are always exceptions! Some birds get along with other better ... some birds scratch more than others, then of course is the weather ... and actual yard location.
Another factor in the size equation ... is what size of birds are you talking about? Giant 13-15 pound birds? Or One pounders? ... ???
When faced with a limit of birds by law ... there are ways to cheat the size "rules" ... by getting smaller chickens, if you already have a tiny coop, just get tiny birds!
Most "Large Fowl" (LF) (regular sized chickens) will range from 4-9 pounds ... "Bantam's" are just tiny size versions of the LF, usually 1/4- 1/3rd size of the LF counterparts. While there are some breeds that are only available in bantam size.
So ... without knowing what the purpose of you getting chickens ... I'd say 2, maybe 3 at most LF hens could work in that coop, I would definitely remove the dividers on one bank of the nesting boxes, and open that up to the "floor space".
While under the deck run area is tempting ... what you have to decide is ... do you want to have to crawl under there to retrieve a chicken, or eggs?
I would suggest putting in a ground to bottom of deck fence to restrict chickens going any farther under than say 2'.
For the run I'd suggest you get a 100' long roll of 5' tall 1"X3" 14 gauge "welded wire" fencing ... "T-posts" will hold it up, set it up in a 25' square around the coop, using part of it under the deck ...
For ventilation I'd try to see how the windows were installed, and try to remove them in one piece, then put hinges at the top of them, and install 1/2" hardware cloth on the inside of the coop, to keep critters out while windows are open ... also looks like your barn coop would benefit from a cupola for added ventilation.