I only had an interview with a Senior Scientists from the department that I was to work with. Never spoke or interviewed with the department manager, never interviewed or heard anything from the HR apart from the legal documents they required me to sign. The interview was supposed to be a brief and informal discussion about my background and what the project would be about. But turned into a a super deep scientific discussion, almost exam like on the spot. Not very pleasant experience, super stressful and I surely didn't expect to get an offer, even though I did.