Having one Croatian in every team that have won the champions league from 2013 is just a coincidence.
Of course it is just a coincidence and it doesn't mean that team has to have Croatian player in order to win Champions League but it is interesting anyway. If anything, it says that Croatian players play in the top world team, therefore they often win CL.
I can' believe that people thought that there is actually something behind it and that I have to further explain this piece of trivia...