How many chickens do you have?
A common rule of thumb is 4 square feet per chicken in the coop (sheltered area for sleeping and for hanging out in bad weather), and 10 square feet per chicken in the run.
It looks like that one is about 3 feet by 6 feet (for the entire structure.) That is 18 square feet. As a run, it is almost big enough for 2 hens. If you put it somewhere sheltered enough that they can use all parts in all weather, and you never close the pop door to the little top area, the whole thing could be considered the coop, and then it would be big enough for 4 hens. But to keep 4 hens in it, you should add an additional run with at least 40 square feet.
I don't see dimensions for the little sheltered house part at the top. If that needs to function as the coop (where the chickens spend days in bad weather, in addition to sleeping in it), then I would expect it to be big enough for one, probably not even two.
When the website says it holds 6 chickens: either they are figuring bantams (extra-small chickens), or they are using numbers for overcrowded commercial conditions (the kind that backyard keepers do not usually want for their chickens.) Apart from keeping the chickens happy, more space makes them less likely to peck each other, injure each other, and even kill each other. Small spaces also need cleaning more often, and are more likely to stink because of how many droppings in how small of an area.
