Hi, I was just having this problem myself.
I got it to work by opening a new Finder window and locating the app wherever you saved it when you downloaded it (e.g. for me, it's in the 'Downloads' folder). Then, you ctrl-click (^ - click) the app and a different pop-up should appear and you should be able to open it from there.
I read that this is essentially making an exception permissions-wise for the program (it works for similar other finicky apps as well).
Hope this helps