how to open existing source code or project in unity?

i have bought some source code and i have tried to open the source code with unity.
step as open project ---->folder location\Assets\Scenes. it show selected folder is not a unity project or open scene ------> folder location\Assets\Scenes\MainScene or MenuScene unity file. however, nothing show up. anyone can help me?

Thanks!

A scene is a scene, a project is a project. You can’t choose a scene if you want to load a project, and vice versa. If you want to load an existing project, just select the uppermost folder, the one that has the child folder “Assets”.