Log of the second error, which may be a follow-up because the engine is installed in “Program Files (x86)” is:
“\Epic” kann syntaktisch an dieser Stelle nicht verarbeitet werden. C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(42,5): error MSB3073: Der Befehl ““C:\Program Files (x86)\Epic Games\4.10\Engine\Build\BatchFiles\Rebuild.bat” TwinStickShooterEditor Win64 Development “D:\Projects\Unreal\TwinStickShooter\TwinStickShooter.uproject” -rocket -waitmutex -2015” wurde mit dem Code 255 beendet.
This is German for (roughly) “\Epic” cannot be syntactically processed at this position. C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(42,5): error MSB3073: The command ““C:\Program Files (x86)\Epic Games\4.10\Engine\Build\BatchFiles\Rebuild.bat” TwinStickShooterEditor Win64 Development “D:\Projects\Unreal\TwinStickShooter\TwinStickShooter.uproject” -rocket -waitmutex -2015” exited with code 255.
It seems that the “(x86)” in “C:\Program Files (x86)\Epic Games\4.10\Engine\Build\BatchFiles\Rebuild.bat” somehow messes up the command, because the brackets have a special meaning. Note that there are quotation marks around the Rebuild.bat filename, so the spaces in the file name should not be the problem.
I will reinstall and manually change the directory of the launcher to somewhere on D:, but maybe you could have a look at this problem.