Since the film is relatively recent and not a major Hollywood production, this information will not be on IMDb or Wikipedia. You need to search in Serbian/Croatian/Bosnian (BCS) on regional platforms.
Exclusive castings in Serbia typically last only 48 to 72 hours. Zauder Film has implemented this model to avoid the chaos of thousands of unprepared applicants. They want serious actors only. The casting directors have hinted that they are looking for:
English search won't work well. Use these phrases: zauder film srpski casting exclusive
If you speak/read Serbian, go to YouTube and search exactly this phrase (copy-paste):
"Zauder" kasting ekskluzivno
Sort by Upload date (not relevance) and scroll back to 2020–2021. That is your best chance to find what you are looking for.
Selected candidates will be invited to the Zauder Film studio in Zemun. Here, they will read opposite established Serbian actors who are already signed to the project. Rumor has it that renowned actor Sergej Trifunović is attached to the film, though this remains unconfirmed. Since the film is relatively recent and not
If you want to be part of this exclusive event, you need to move fast. Here is the verified application process as of this month: