While still a child, he showed musical inclinations and an affinity for the traditional strains of the Croatian people. His institutional musical education started in 1910 in the school of the Croatian Music Institute in Zagreb, as regular pupil of composition and orchestration in the class of Vjekoslav Rosenberg-Ružić. In 1910/11, Žiga was recorded as being a timpanist in the student orchestra conducted by the same teacher. He learned music theory (harmony and choral singing) from Ćiril Junek, and piano in the class of Sidonija Geiger. From 1912 to 1914 he had lessons in the clarinet in the same school, class of Stanislav Krtička. In 1914 –1916 he was in Varaždin, at the recommendation of Rosenberg-Ružić and Geiger, and was a member of the Orchestral Association there. When the Croatian Music Institute acquired conservatory status in 1916, Hirschler returned to Zagreb and went on with his study of composition with Rosenberg-Ružić. He first appeared in public as composer and conductor on 13 June 1917 at his graduation concert, and the final production of the Conservatory. On that occasion he conducted the Student Orchestra in performances of his own works: Overture in E Minor and First Suite for Orchestra in G Major.