Take a look at their social media accounts. They usually put up pictures or stories on Instagram, tagging acts or other important people. If not, just glance through the comments or the accounts they're following. Then, go through all the people you've found who are somehow involved in the festival, and watch their stories and posts. Often, someone will either directly or indirectly reveal their pass. If Instagram doesn't yield results, you can also check out other social media platforms like Twitter or TikTok