You have a right to work after nine months has passed since you submitted your application for international protection.
After these nine months have passed, it is not that hard to find a job, but unfortunately, these jobs are usually not highly paid. You typically need to know some basics of Croatian to be employed.
In the meantime, while you are waiting nine months to pass, you can get in touch with active organizations in Zagreb who assist migrants. Some of them have projects through which they support in the process of finding a job. As an excellent tool to get the now the system you are in, you can look at the so-called Danube Compass that will give you an overview of all the information that you need to know about employment in Croatia.
You can find it here: http://hr.danubecompass.org/archives/situation_category/work