Hey there,
I tried building the unreal engine 5.1.1 from source but after opening the solution file via Rider I get 5365 errors for thousands of build.cs files. I read through the docs and followed the instruction of installing all required components for vs.
Am I missing something?
Verify that you have installed all required components for Visual Studio: Make sure that you have installed all the necessary components for Visual Studio, including the C++ development tools, Windows 10 SDK, and other required packages. You can check the Unreal Engine documentation for a list of required components.
Sometimes, errors can occur when there are conflicts or errors in the build process. Try cleaning and rebuilding the solution to see if this resolves the issue.
Finally, check conflicting software like firewalls, or antivirus. Check if you have correct environment variables and read the documentation if you have missed any steps.
Good luck Unknown! 
As far as I know, these are the only required components for Visual Studio, if Im following the Github readme:
Do I need more or some others they didnt mentioned?
I suggest you follow this guide: Building Unreal Engine from Source | Unreal Engine 4.27 Documentation
