Hi Annabelle! I used to have this problem with my old MacBook Pro! Have you tried changing your security preferences? I found a link for you with the steps on it: http://www.tech-recipes.com/rx/45404/mac-downloaded-app-is-damaged-and-cant-be-o...
Hello! Thank you for your quick help :D It was that issue, but for some recent, Sierra/High Sierra have the "Anywhere" option hidden, so I had to use the Terminal to get it to reappear! And now it's stopped giving me that error, and it lets it open, but then... nothing shows up. The icon just sits in the dock and no birds are fed! My apologies for coming to you with more errors, and thank you again for your support!
Sorry to hear that didn't work, I'll keep looking into it and get back to you shortly!
Have you tried running in safe mode to see whether it runs that way or tried using it as another user? We're still currently looking at other options, sorry for the inconvenience!
Hi Annabelle, we're on our way to making a new version. Hopefully this one will work! We'll be sure to message you as soon as it is released! Thanks for your patience.