Simply Fortran for Windows installs as an MSIX package, which places everything under
C:\Program Files\WindowsApps
. The new compiler should be available on the PATH as well (as gfortran). There should be an entry in the Start menu for the new development environment (listed as Simply Fortran). You'll probably have to use Windows 11 search to find it right off the bat if it isn't listed as "new" or "recently added."
There should be two "Simply Fortran" entries on Windows 11 in the list of installed apps. Unfortunately, Microsoft has decided you don't need to see the version anymore, so you would need to right click and select "More Info" to see which version each refers to. It's not ideal. We'll look into making that a bit better.
But yes, they should be usable as separate programs. Neither overwrites the other. You can reinstall version 3 safely even though version 4 is present too.
Jeff Armstrong
Approximatrix, LLC