i watched the blender guru filmic blender video and then i tried to play with color management , but i found that the filmic log color space is already there in the blender , so is this the same color space as he is talking about in the video - https://www.youtube.com/watch?v=m9AT7H4GGrA , although u tried to install the space from github but failed
If you keep watching the tutorial, Andrew did mention that it is included in newer Blender and no need for the addon.
And also in the video description:
The Filmic addon is no longer required and will actually potentially cause some compatibility issues with other addons. Filmic is now included with Blender by default and can be configured via the color management panel.