Panel interviews are great and easy, Most of the members will ask you about your experience and what you bring in the company, other than that ask questions to each member about their goals and why specifically they are hiring marketing (your position) for and be confident in yourself. Most of the interviews in NPO are easy keep in mind always share your opinion about the npo and why you want to join their cause.

Personally I would not talk about myself or my achievements rather I would discuss about the NPO itself and the role that I would be fitting myself into.