Ajax Growing up in
Brestovec Orehovički, Kotarski started training with his local club NK Tondach Bedekovčina at the age of 6. After impressing, he moved to
Dinamo Zagreb's academy in 2011. On 7 July 2017, he signed his first professional contract with
Ajax but had to wait until he turned 18 to officially sign with the club, and he is contracted until 30 June 2023. Kotarski made his professional debut for Jong Ajax in a 3–0
Eerste Divisie loss to
Jong PSV on 30 March 2018. Kotarski was made the third keeper of the first team ahead of the
2018–19 Eredivisie season. Due to good health of first and second choice keepers
André Onana and
Kostas Lamprou, he continued to ply his trade with the reserves.
Gorica (loan) On 16 June 2021 it was announced that Kotarski would be loaned to
HNK Gorica on a season-long loan spell, competing in the
1. HNL, the top-tier of professional football in his native Croatia. He featured 24 times in the league and 4 times in the
cup, keeping a clean sheet in 8 of those matches.
PAOK Οn 27 June 2022, Kotarski signed a four-year contract with Greek club
PAOK.
FC Copenhagen On 9 July 2025,
Danish Superliga club
F.C. Copenhagen announced the signing of Kotarski on a five-year deal. ==International career==