Can't Register for Betheme Support

Hello! I have an account with Envato Market and Themeforest and I have recently purchased Betheme. I am trying to register for the Betheme Forum so I can post questions and see answers to the others questions. It will not let me register for the support, it keeps giving me an error saying my ThemeForest username is incorrect and everything I have entered is correct. Any guidance is appreciated. Thank you!

You should contact their support ( or theme author ) instead of posting here at the forum