It’s time to compile the editor! In Visual Studio, make sure your solution configuration is set to Development Editor, and your solution platform is set to Win64. Right click on the UE4 target and select Build.
When you are building the Engine from source code, the solution configuration in Visual Studio should be set to Development Editor. The Development configuration (as well as Debug, DebugGame, and Shipping) are used when you are getting ready to package your project. When you are at that point and ready to start creating packaged builds of your project, you would set the configuration to Development and build the project in Visual Studio, then package it. If you ran into trouble building your project in Development configuration, that is a separate issue that we would have to investigate.
The results of building using the different solution configurations can be a little bit confusing. We do have some documentation pages that explain the configurations when building projects (a little out of date) and when building the Engine (really out of date). I am putting in a request for our documentation team to get these pages updated with current information, so keep an eye on them.
Please let us know if there are any specific areas of the documentation that are confusing to you.