Putting together an event requires teamwork, and most applicants work with many other people to organize their event, however keep in mind that the ambassador program application itself is about your individual experiences and your personal story. It is important that you convey that in the application. Why do you, as an individual, deserve an award?
It is also important that you have your own role in the event. While there are no specific requirements for the size or type of event you have to organize to be eligible for the scholarship, the review board will be reviewing the essay and the marketing/fundraising strategy to ensure that you put significant effort into making the event a success.