Open a Mac app from an unidentified developer
If you try to open an app by an unidentified developer and you see a warning dialog, you can override your security settings to open it.
Apple Support
If you try to open an app that isn’t registered with Apple by an identified developer, you get a warning dialog. This doesn’t necessarily mean that something’s wrong with the app. For example, some apps were written before developer ID registration began. However, the app has not been reviewed, and macOS can’t check whether the app has been modified or broken since it was released.

A common way to distribute malware is to take an app and insert harmful code into it, and then redistribute the infected app. So an app that isn’t registered by an unidentified developer might contain harmful code.

The safest approach is to look for a later version of the app from the Mac App Store or look for an alternative app.

To override your security settings and open the app anyway, follow these steps: