I’m cloning the Unreal Engine source code from GitHub. I’m downloading the content samples from the Unreal Engine Launcher. Do I also need to install the Unreal Engine from the Launcher? “Not ready” is displayed against the sample project I have already downloaded.
That is probably happening if the Launcher cannot find metafiles it uses to actually determine parts that are downloaded and ones that are missing. Those files also determine what gets updated later on as well.
They reside in ~/Library/Application Support/Epic in OS X, and C:\ProgramData folder in Windows (sorry don’t know the exact path, I’m using OS X right now).
You could try straight replacing the downloaded binaries with the source code compiled ones and see if that works. I do not have knowledge of how the Launcher’s update system works and whether this swap would actually disturb the metafiles though (it might if they use some kind of a checksum).
Overal, I believe there might a disconnect between using the pre-compiled binaries and the source code ones that Epic would need to address at some point.