See V6 Mac OS X installation here: https://simcur.zendesk.com/entries/21545386-OSX-Mac-installation
I downloaded starrynightcelestronse7.dmg to my desktop. It took several hours. I double-clicked on the .dmg. A window opened. I double-clicked on the .pkg icon in the window. A dialog box opened saying "Verifying "Install Starry Night Celestron SE 7.pkg"". The thermometer never showed any blue for many minutes. So I clicked on the circled x at the right end of the thermometer and tried double-clicking on the .pkg icon again. Same thing.