Notarization and Hardened Runtime:
With the release of macOS 10.14 (Mojave), Apple released "notarization" as well as "Hardened Runtime." This is a way for macOS to identify an application as being from a verified developer and apply restrictions on how an app is to be processed. This prevents the execution of malicious code on your system. Although this technology was introduced in 10.14, it was not required.
With the release of macOS 10.15 (Catalina) in the fall of 2019, .dmg files that are not within compliance of Apple's security guidelines will fail to install.
Hardened Runtime: This is a way to set a flag in the code of an application to apply a number of restrictions to an app when the application is processed.
Notary Service: This is a way for Apple to use a service to scan applications for malicious code that have opted into "Hardened Runtime."
What this means for Studio One version 4.5.3 and above:
This means that the .dmg for the application is now notarized and is compliant with Apple's security guidelines. Upon launching the program, Studio One will simply open as designed, without requiring any configuration to security & permission settings on your Mac.
If you are trying to load 3rd-party plug-ins, the plug-ins must be properly signed, otherwise you may receive one of the following error messages:
If you do receive one of the errors above, you will need to contact the manufacturer of the 3rd-party plug-in for more information.
If you do install a previous build and you are running macOS 10.15 (Catalina), you will need to ctrl+click the .dmg and choose to open with DiskImageMounter. Once installed to your Applications folder by dragging the app into it, you can open the app and click 'Open' when the error is thrown. You can also navigate to the System Preferences > Security & Privacy, unlock as administrator, and hit "Open Anyway" to suppress the warning.