Engine do not detect previous version downloaded from gitHub

Hello guys,
I work with a team with unreal to create a full game. We decided to use version 4.20.2 but unfortunately i updated my version to 4.20.3. Now i try to come back to the previous version and to do so i downloaded the 4.20.2 from gitHub. The problem is when i copy the folder in the Epic Games folder in program files it just do not see it. I also followed this tutorial : The launcher doesn't recognize versions already installed in requested folder - Getting Started & Setup - Epic Developer Community Forums but the engine still download the 4.20.3 version.
Someone have a solution ? I spent two days on it, i’m about to cry my whole life ^^ Thanks for help !