Sandboxing provides the app with everything it needs to perform its purpose and nothing else. To prevent signed apps and those distributed via the Mac App Store from damaging the operating system, Apple uses sandboxing.
To circumvent Gatekeeper, go to System Preferences > Security & Privacy, and then click “Open Anyway” after you attempt to open an unsigned app. Developers who create free, open-source apps often cannot justify the $99 required to enter the Apple Developer Program and issue certificates.
By default, macOS blocks all software that isn’t signed with an Apple-issued developer certificate or downloaded from the Mac App Store. Another technology called Gatekeeper tries to prevent unknown applications from causing harm.