ISB Interviews can be intimidating for many applicants, primarily because it's a panel-format, and due to in-built pressures to get in.
A good way to navigate this is to prepare your answers along with relevant examples/storylines for some of the common questions:
Why MBA?
Why ISB?
What do you bring to the table?
Why can't you reach your goal without ISB?
What are your strengths and weaknesses?
Once you have these prepared, it's a good idea to plan for some mock-sessions with alums to practice your interviewing muscles. This can massively help in calming your nerves on the day of interview, and you'll be able to do well.