Your link is broken. There is a space after the com that should not be there.
There are a whole lot of things that go into how much space you need, especially climate and how you manage them. The generic guideline is 4 square feet in the coop with 10 square feet in the run for each full sized chicken. This will keep most of us out of trouble in many different circumstances, but if you have weather or management practices that keep them confined to the coop portion only for extended lengths of time you might run into problems with this many. On the other hand, if they have access to that run 365 days a year and you don't sleep in on a Saturday all that much and can find someone that will get there early to let them out when you are gone on vacation, you can probably go with another one or two.
So I would say you probably have room for 4 chickens in there. You might be able to squeeze another one or two in there depending on your management practices and climate, but I find that the more extra space I give them, the less I have to work taking care of them. For example, think in terms of shoveling chicken poop.
Hope this helps a bit.