Damaged Kodi.app

Hey guys. I am trying to install Kodi Krypton. I unistalled the Jarvis version and had tried the Krypton once, but the instructions I followed on setting up weren’t working, so I uninstalled it again and tried reinstalling. The message I get now is this:

“Kodi.app” is damaged and can’t be opened. You should move it to the Trash.
Firefox.app downloaded this file today at 2:51 PM from mirror.jmu.edu

Any ideas? I miss my Kodi.
Thanks
Rhonda