Kolmanič joined ATXFC in March 2021, and in his first four seasons with the Club, recorded nine (9) assists in 73 total MLS appearances (47 starts) for the Verde & Black. In January 2025, he signed a contract extension guaranteed through 2026 with an option for 2027.
Prior to arriving in Austin, he spend the 2017-2021 seasons with NK Maribor in his native Slovenia. He made 45 appearances (43 starts) and contributed six (6) assists across all competitions with Maribor, helping the club capture the 2018-19 PrvaLiga title. Kolmanič also made seven (7) starts in the UEFA Youth League with the NK Maribor U-19 side.
At the international level, Kolmanič was called up to the Slovenian senior men's national team for the first time in October 2021, and made 39 combined appearances with the U-21, U-19, U-18, U-17 and U-16 Slovenian National Teams.
