The HR approached via email. They asked for open dates for 2 weeks, but the final interview was arranged in 3 weeks. It was a phone interview. They will mostly pick a day convenient to them, even if they ask for your availability, so be prepared.
The Hiring Manager was very punctual to call on the decided time. The interviewer gave good information about the company at the beginning of the interview. And a feedback about the interview at the end. He will tell you right away if they are moving forward or not with your candidature.
Interviewer, was stern professional. It was a grilling and slightly stressful interview, where they question your thinking, logic and your ability to defend yourself.