In the Running Out of Corra section on page 6 of the rulebook, it says that if there is not enough Corra in the supply for all players to take all Corra owed to them, “players will distribute in player order (AI last) until the stockpile is gone.” This is done one Corra at a time.
So in a 4 player game, if each player is owed 2 Corra and there is 3 Corra in the supply, players 1-3 would each receive 1 Corra.