Open UE4.sln in (ensure the Game Development with C++ workload is installed offline).
For the launcher on the offline computer to recognize the copied files without forcing a re-download, you need the manifest file. unreal engine 4 download offline installer extra quality
Open the extracted repository folder on an internet-connected machine. Run Setup.bat (Windows) or ./Setup.sh (Mac/Linux). Open UE4
If you cannot access the organization-level installer, downloading the source code from GitHub allows you to build a completely independent version of the engine. unreal engine 4 download offline installer extra quality