You have a Microsoft 365 E5 subscription that includes Teams. All users are assigned the Teams Premium add-on license. You need to enable an event that supports 20,000 streaming participants and…

Controlled-content meetings are a type of meeting policy for sensitive content, not a specific meeting template designed for large-scale broadcasts with eCDN.

Virtual appointments are optimized for one-on-one or small group consultations, not for large events with thousands of streaming participants.

Teams Town halls are designed for large-scale broadcast events, supporting up to 20,000 attendees with a Teams Premium license and natively integrating with eCDN providers to optimize streaming performance for large audiences, directly meeting the specified requirements.

While webinars support larger audiences than standard meetings (up to 1,000 interactive participants), they are not the primary solution for 20,000 streaming participants with eCDN integration, which is a key feature of Teams Town halls.