You must be doing something wrong – not using the recommended tool chains, not using the recommended scripts, having a broken operating system install, or something like that.
Assuming you build from a release branch, on a supported OS, with a supported, correctly installed tool chain, the scripts work with no errors.
Regarding “built from source” – the binary you download in the launcher is built from source. What you seem to want, is “built from source, but with certain defines changed to support dedicated server” – this is not something you can separately download; in fact, I would think someone providing that would be going against the Unreal Engine licence (no redistribution of source code allowed.)