4x8=32 sq ft.
10 sq ft per bird is the minimum space recommended. Or 14 sqft per bird because usually the ten assumes 4 sq ft if coop space too. That is space not taken by food dishes or waterers or nests.
So 3 birds. At the most. The smaller the numbers and space, the more important it is to have at least the minimum..
It helps that they can have more space every third day but it does not average very well. The space is not just for exercise, dust bathing, scratching, foraging, and such.
It is also so a lower ranked hen can signal to a higher ranked hen that she accepts the ranking. The higher ranked hen will not take into account that the others are giving her as much space as they can; only whether they are respecting her position. Even if they are all docile enough and skilled enough to not demonstrate behaviors people often call "bullying", it is still stressful.