Ue4prereqsetup-x64.exe -

If you cancel it, the main application (UE4 Editor or game) will likely crash on startup with errors like:

The file ue4prereqsetup-x64.exe is directly associated with . It is an installer for the prerequisite software packages required to run Unreal Engine 4 applications or the Unreal Editor itself on 64-bit Windows systems. ue4prereqsetup-x64.exe