The owner of an occupied cloister earns extra VP for sets of 3 like island tiles. For 1 set of 3 like tiles, they earn 1 VP, for 2 sets of 3 like tiles, they earn 3 VP, for 3 sets of 3 like tiles, they earn 6 VP, and for 4 sets of 3 like tiles, they earns 10 VP (the maximum).
Example: Todd has an occupied cloister and 6 forests, 3 quarries, 2 corn plantations, and 1 coffee plantation at game end. He earns 6 extra VP.