Thanks for reporting it, I will look into this issue and possibly fix it or at least add a note to the download link.
downloading in Opera
saved MSI as EXE - won't instal - how to fix
Dunno if this is a problem with Opera or your site/software:
i tried to download RWCursorEditor32.msi in Opera and it saved as EXE, which wouldn't install. Manually renaming it to MSI fixed the problem.