The only formal 'institution' of the school for which there is evidence is the scholarchate. This is consistent with the fact that all scholarchs in the first two hundred years or so of the school's existence are non-Athenians. By c. 270 BC Stoicism had become the dominant philosophy in Athens. The cosmos lives, and is morally perfect.
Fate predetermines all.
Goodness and happiness are obtainable by living in rational harmony with that preordained nature. The Hellenistic Philosophers 1987.