The coop is probably adequate for 6 hens IF they are NEVER shut into the house part, and IF they are in a climate where they can use the wire-fenced part all day (no extreme cold or wind.) So the manufacturer is sort-of right under certain very limited conditions.
If the chickens ever need to stay in the wood part (shut in at night because of predators, or choosing to stay in during the day because of bad weather), then that little house is only big enough for about 2 full-size chickens, maybe 4 bantams.
So how many chickens can live in that coop depends on how you view it. Either it's a nice-sized coop with great ventilation (wire walls) and a cute little nesting/sleeping cubby, or it's a tiny little coop (wood part) in a small run (wire part.)
If the chickens ever need to stay in the wood part (shut in at night because of predators, or choosing to stay in during the day because of bad weather), then that little house is only big enough for about 2 full-size chickens, maybe 4 bantams.
So how many chickens can live in that coop depends on how you view it. Either it's a nice-sized coop with great ventilation (wire walls) and a cute little nesting/sleeping cubby, or it's a tiny little coop (wood part) in a small run (wire part.)