I had 1 interview. Normally it is one interview, I think. I remember admission consulting sessions with HKUST mentioned that. Those of you who have dates starting at Nov 30 probably because the previous slots were filled. When I register for mine, I saw multiple slots at different dates. They probably send invites out in batches. But mostly right after they have all your supporting documents listed on the portal.
Honestly though, the application process is pretty straightforward, and the portal is easy to use. Admissions are also very friendly and responsive to questions. Though I think they could do better in advertising the school program in more details. As it stands, the website is pretty vague in terms of campus life, activities on campus etc. The only thing is that I felt the interview is pretty scary haha. It is conducted by 2 profs and admissions listening in. There is a lot more digging I feel in your profession. Perhaps my work experience is a bit different. No big brand names.
Honestly, the best advice is probably to be yourself. Just have a fun conversation. Let admissions do their job whether to take you or not. Most importantly, just enjoy the whole process. What is done has already been done. The interview is really to put a face to an app and see if you are who you claim to be.