The interview is position-specific. The final decision depends on the Principal Investigator in a given research group. Therefore, it is all about getting their approval. Some PIs expect research papers in your CV, others don't and they fully rely on your academic curriculum and attitude.

The first round was quite casual. They asked about my CV and background. And why do a PhD? Explained more about the project. At last, I asked questions. It lasted around 45 minutes.