Impossible to complete the operation (OSStatus error 99999.)

Hi,

I have downloaded an app from the internet, but whenever I try to to open it, I get the message: Impossibile completare l'operazione. (OSStatus errore 99999.). It's in Italian, but it basically means that I can't complete the operation of opening the app for some reason. I tried to work on the privacy settings of the System Preference but nothing works, I disabled firevaul or firewall. How can I fix this? My laptop is macOS Mojave, 2019.

Thank you.