PoliCultura is a collaborative digital storytelling program for schools (K-12), which has gathered so far more than 41,000 students. It is an example of authentic learning experience, for a number of reasons, including the fact that students are required to do a "professional" work that will be made public in the frame of a competition. The paper investigates whether PoliCultura can foster creativity, by analyzing all the "stories" submitted to the competition in 2020 using a literature-based creativity rubric, with positive results. The analysis of the teachers' pedagogical reports sheds light on the key factors for promoting creativity, which are, for the teachers: to be a facilitator of the activity, to promote collaboration, to "open up" to external support and stimuli beyond the classroom and to foster the students' individual talents. Guidelines for designers of educational tools are drawn too: provide a clear path while at the same time allowing a wide degree of freedom, keep the threshold low and plan for the teacher to be at the center-stage.