Hi A.Shakhidov95,
You can’t load projects made in more recent versions - you can only load it into later versions. e.g. a 5.1 project can be loaded into 5.1 → 5.3 but not 4.27
by default when you download the engine :
documents > unreal projects > {your_project_folder} > right mouse button click the : {your_project}.uproject > Switch Unreal Engine Version