You can just download the 4.19 from GitHub and recompile it, nothing difficult if you already have compiled a project with plugins in Visual Studio before. Usually you just change the project .uproject file to 4.20, save this file, right-click it and choose to regenerate the visual studio files, then you open the .sln file with Visual Studio and choose rebuild, save all and then you can open the project .uproject in UE editor normally.