[Mac Demo refuses to start after unzipping]

Had the same problem at first but I managed to figure out what caused it. I unzipped the file with Keka at first and when I tried to open Nimbatus.app I got the same error. So here is what I did to fix it:

 

1. Unzip the zip file with the build in archive app from MacOS

2. Right click Nimbatus.app and Open

 

That's pretty much it, hope it could be of use to someone.

 

Yup, this also worked for me.

[Mac Demo refuses to start after unzipping]

I'm having the exact same issue, this is the message I get and I have the permission granted for unsigned apps to run.