Working in Austria
Due to § 4 Austrian Act Governing Employment of Foreign Nationals (BGBl. I Nr. 66/2017, effective since 1.10.2017) all students from so-called Third Countries (=non-EU Countries) in Austria are allowed to work up to 20 hours per week alongside their studies.
Therefore your employer needs to apply for a work permit at your local Public Employment Service (AMS). In Vienna the AMS regional office at Ungargasse 37, 1030 Vienna is responsible. There you will also find the Service Ausländer_innenbeschäftigung Vienna. A labour market examination is not necessary.
For further information please see http://www.migration.gv.at/en/types-of-immigration/permanent-immigration/students-and-graduates/
Job search in Austria
The following online platforms offer part-time jobs, jobs in the cultural sector:
Job platform of the student's union: https://schwarzesbrett.oeh.ac.at/jobs/
The Willhaben platform: https://www.willhaben.at/jobs/
For all kinds of jobs in the cultural sector: https://kulturkonzepte.at/service/jobboerse/
Platform and newsletter for jobs in the cultural sector: https://kupf.at/kulturjobs/#aktuelle-kulturjobs