Installing Unreal Engine (source version)
This page provides instructions on how to download and install the UE4 source version.

Why would you install the UE4 source version instead of the regular UE4 binary version from the epic games launcher? Well...
You don't have to download the source code to work with Unreal Engine 4. However, if you are planning on building dedicated servers for your Multiplayer Game(s) then the Unreal Engine Source version install is required. If you want to install the regular binary version of UE4 then click here. You can also install both.
UE4 Source version will take up around 100-135gb of disk space and the average project size is increased with a minimum of 10GB's aswell.

Follow these instructions to get acces to the Unreal Engine Github repository where you can download the UE4 Source Code.
If you do not follow the above instructions then you will get an error page when trying to acces the UE4 Git repository.
If you have properly followed the above instructions then you can download the source code from this page https://github.com/EpicGames/UnrealEngine by using the instructions below in step 2.

You'll notice that the repository has multiple branches that you are able to download. We recommend that you download the release branch. The release branch is extensively tested by Epic Games.
Click here to download the Release branch.

Download the Source Code ZIP file and unzip it in your Local Disk (C:) Main Root folder. (This is recommended for optimal performance and to avoid any bugs/errors).

Now that you've downloaded and set-up Unreal Engine, you're ready to build the engine from source. Follow the instructions below.
Please make sure you have installed Visual Studio 2017 or 2019 for Windows Desktop before proceeding. This is required for packaging games with Unreal Engine and for installing the UE4 source version. To properly install Visual Studio 2017 or 2019 with the required UE4 settings checkout:

Open your source folder in Explorer and run Setup.bat. This will download binary content for the engine, as well as installing prerequisites and setting up Unreal file associations.
When you are running the Setup.bat you might get a few errors in the command log instructing you to download (extra) components in Visual Studio. Simply follow the instructions that the command log might prompt to you.
A clean download of the engine binaries is currently 8-11gb, which may take some time to complete. Subsequent checkouts only require incremental downloads and will be much quicker.

Inside the root directory of the source code folder, run GenerateProjectFiles.bat to create project files for the engine. It should take less than a minute to complete.
This information is important for building you game in the future You must generate project files each time you sync a new build to ensure they are up to date. If you delete your Intermediate folder, you must regenerate project files using the 'GenerateProjectFiles.bat' batch file.

Load the project into Visual Studio by double-clicking UE4.sln in the root folder.

Set your solution configuration to Development Editor.

Set your solution platform to Win64.

Right-click the UE4 target (found in the solution explorer on the right) and select Build.
Building the UE4 source code might take anywhere between 10 and 40 minutes to finish, depending on your system specs. Older hardware might take up to 2-5 hours to compile.

Set your startup project to UE4.

Right-click the UE4 project, hover over 'Debug' and click 'Start New Instance' to launch the editor.

Congratulations! You've compiled and launched the engine from source.

The Source Version of Unreal Engine is required for creating dedicated servers for multiplayer games.
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Important information
Step 1: Get acces to the UE4 Git repository
Step 2: Select the right Source Code Branch
Step 3: Download the Source code ZIP file
Step 4: Building Unreal Engine from Source
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Running the Editor
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You have now installed the source version of the engine!