You need to relax the GateKeeper settings.
You can read about it here.
Searching towards the bottom is: "How to open an app that hasn’t been notarized or is from an unidentified developer".
Generally it takes us a little bit of time to verify everything on a new OS. For production scientific computers, I would recommend waiting some time before upgrading to a new OS release. Other softwares, such as Freesurfer, have been shown to be susceptible to changes in OS version due to dependency changes and will give you different numbers.