The fan won't come on for the humidity setting unless the coop gets 70 and sometimes we've had to shut it off as it would be counter-productive. It's sort of rare though as the coop with 14 chickens in a 5x12 coop stays relatively dry now.
For in the coop dryness, we use horse bedding pellets...
I saw all the replies, and you got some excellent advice. That's a cute coop, and going to be so much nicer once you have it spiffed up. We're up in WI where avg. daily RH is 81%, and mold starts at 70%, so we have to watch for that in the coop. We put an industrial-type digital exhaust fan...