This comes up a lot.
Bottom line, the evidence for actual chickens being actually-harmed by cedar shavings bedding is not overwhelming (it seems to be a rare occurrance and mainly associated with insufficient ventilation)/ And in any case cedar LUMBER is a different species of cedar that what the bedding shavings are from.
Basically, to be on the safe side, if the thing smells strongly like a cedar closet then you should either air/age it til it doesn't, or I suppose you could paint or otherwise seal it if it's super bad and you're in a hurry.
Otherwise, no problemo.
You should have good ventilation *anyhow* (note that many of those commercial coops don't really have very good ventilation, I haven't looked at that particular link tho), for other reasons.
Good luck, have fun,
Pat