You cannot participate without it. Go to the App Store and download the official app from Apple.
Below is a deep-dive article into the world of YouTube Beta testing, exploring how it actually works, the illusion of platforms like TestFlight, and why the distinction matters for creators and power users. youtube beta testflight
Because the official YouTube TestFlight is so exclusive, scammers have flooded the market. Be aware of: You cannot participate without it
💡 If you don't update the app or open it for several weeks, Google may remove you to make room for active testers. Open the app at least once a week to stay "active." exploring how it actually works