thank you for responding - according to the website which opens up at
completion I have successfully have gone through the entire install process
however it is not in my applications folder or indeed elsewhere - I am
downloading the G4 version

I don't think the plug-in can auto-install on Mac (which you're glad of for
security reasons.

Try double clicking on the installer and following any instructions. You'll
probably need to enter your OSX password,

Then quit your browser and reopen it.