Well to start with the HR's do not give you a clear picture of the interview process. The least you can expect from them is to explain the interview process. HR would give you wrong JD all the time, and expect you to give ad hoc interviews. Imagine the plight of the candidate who has to deal with unstructured organisation ways of working. Sales interview meant more like marketing interview.

Nothing crazy, typically 4 or 5 interviews which will focus on your knowledge and experience in programmatic/ad tech. Majority of questions will cover client/agency contacts and history working with any hold co's, independent agencies.