It was very casual. CALPIRG encourages entry-level applicants. Don't worry if you think you don't have the skills, they are eager to train you. Mostly they are looking for people who want to learn and take on challenges. Also, examples of how you have displayed leadership and organizing skills. It's a plus of you have social media marketing experience, and experience doing research and writing reports (which you learned in high school or college). You need enthusiasm to make a difference for the common good.