The tutorial mentions to go into your projects config folder and to the default engine.ini then change over to DefaultGraphicsRHI_DX11.
An example of me doing it:
As mentioned in the tutorial:
Edit “…/path_to_your_UE5_project/config/DefaultEngine.ini” and change DefaultGraphicsRHI=DefaultGraphicsRHI_DX12 to your preferred RHI (e.g. DX11 or Vulkan)
See an example below to use DirectX 11 instead of 12:
[/Script/WindowsTargetPlatform.WindowsTargetSettings]
DefaultGraphicsRHI=DefaultGraphicsRHI_DX11