Protected branches in Organization private repositories


I’m member of larger organisation:

I’ve created private repository there and tried to set protected branch, but i encountered following message

"Protected branches are available to Pro, Team, and Enterprise users
Enforce restrictions on how code branches are merged, including requiring reviews by selected collaborators, or allowing only specific contributors to work on a particular branch."

Contact the owner of the repository to enable protected branches."

therefore I upgraded my personal account from FREE to Pro, but I still can not setup protected branches on that repository I’ve created. How to make this happen ?