Fotomagico 5 cannot even be opened anymore

I want to use my good old Fotomagico 5. I had to reinstall it after my iMac was repaired. I installed it bur I cannot open te app. I get the message ‘No permission to open FM5’. I cannot even get to enter my license key.
How can I get FM 5 started again?

P.S. I had to download FM5 from a website called Mcdownload Informer as sad enough, Boinx does not seem to offer the opportunity to download older versions of FM. This option would be a good service for older users!

You can, indeed download it from the website
Hopefully that will work better for you than the version you got from a third-party.