Can't install download onto two Mac minis, running Mac Big Sur either on Intel of M1

I downloaded the trial software on both machines and all I get when I run the installer is the script launch window with the guide. Nothing is actually being installed. All I can do is 'Quit" the Script Launch window


After running the installer for Mac, you need to add the plugin itself to the plugin manager in Lightroom (file > plugin manager). You may need to navigate in the folders to where the installer placed the plugin file, which should be at “{YourUserName}/Plugins/NegativeLabPro.lrplugin”

(It should place you in the right folder by default when you go to add it, but on some systems, that isn’t happening… so you just need to navigate to where the plugin file was placed by the installer)

See the README file in the download for the full instructions.