This is a standard notification on Apple computers for any and all applications that you purchase outside of the Apple Store.
If you are unable to launch any of the RA Panel installation files in Mac OS and are getting an Unidentified Developer notification, please simply Google how to open applications from unidentified developers in your version of Mac OS.
You can find the latest articles here: Google: How to Open Applications From Unidentified Developers in Mac.
Typically, pressing the Control key while clicking the app icon, then choosing Open from the popup menu, will allow the following notification (see screenshot below), where you can click Open to run the Beauty Retouch, MUA Retouch, and/or Pixel Juggler panels' installer application.
