You need to
- launch Terminal [Applications/Utilities], then type or copy/paste:
chmod +x[including a space after the x] - then drag the app you need to change the permissions straight onto the Terminal window, which will fill in the correct path
- hit Backspace once, as the last task will add an unnecessary space
- Then you need to add the sub-path to the actual executable inside the app, so copy this & paste it onto the end of your current Terminal line:
/Contents/MacOS/* - Hit Enter
- If you did it right, there will be a line that says your Mac name
Then you should be able to open the app
Or you might have to right click the app, click open, then trust this app