As of July 2024, X requires all users to have a Premium or Premium+ account in order to stream to their platform using Ecamm Live (and other similar encoders). You do not need to have a verified account.
X Premium is a paid, subscription service with three levels (Basic, Premium, and Premium+). You can learn more about this service and sign up at https://verified.x.com/
Please note that this requirement does not come from Ecamm. To keep up to date with X's policies, best practices, and general updates regarding live streaming you can follow @Live