Kantar Associate Director interview questions

An interview was lined up but I was to complete an assignment in 90 minutes prior to that. The panel of interviewers was not prepared and they took turns to take the interview ahead with one random question after another! Questions around the specific challenges I faced and learnings from projects I did during 8-10 years ago! No questions around my current role or why am I looking for a change. Questions around the case study I was given the previous day! The case study was itself vague. Hence, I was expected to imagine and create hypothetical scenarios to answer questions around the same spontaneously! The interviewers had their videos switched off so I was literally talking to a blank screen throughout the interview.