I’m not sure why that’s happening. I think it’s an issue with your project’s build properties. Epic gives pretty good instructions on how to set up your project in UE3 if you get the source code from them. I don’t know if this GitHub repo is authorized to redistribute the UE3 source code, even if only for noncommercial use. Why are you trying to use UE3? Why not use UDK or UE4?