There is a much easier way to copy the files out of the Windows Store installation of MSFS; there is no need to install anything.
- Start the sim and enable the Developers Mode via Options > General
- From the dev menu at the top, try to open a project. You will be presented with the standard Open dialog.
- Using that dialog, you can copy any directory in your MSFS installation via right-click, then using the same dialog, navigate to the target directory of your choice and paste the copied content there.
That’s it!