Complex sentence: Kranjčar spent his childhood years in Austria, when his father Zlatko played for Rapid Vienna, thus holding an Austrian passport, counting as an EU player before Croatia joined the EU in 2013.
Split into simpler sentences: Kranjčar spent his childhood years in Austria, where his father played for Rapid Vienna. He therefore holds an Austrian passport, which qualified hin as an EU player before Croatia's admission in 2013.