You may get a pop-up on your Mac when opening one of our installers that it ''can't be opened because Apple cannot check it for malicious software''. This is a typical security procedure that can happen with some macOS versions.
Here is what you need to do:
1) Open your System Preferences and go to Security & Privacy >> ''General'' tab.
2) You need to click on Open Anyway under ''Allow apps downloaded from''. It may bring up a similar dialog with an option to ''Open''. Click ''Open'' and you should be able to start the installation.