Problem with LR Plugins on a new Mac.

I have been using a PC with Lightroom CC, Macphun Luminar and Nix plugins for several years. The PC finally died and I took the plunge and bought a new MacBook Pro.

I logged into my adobe account and downloaded Lightroom CC and Photoshop CC which seem to work ok, even though I didn't see an option to download for Mac or windows and can only assume that the correct version dowloaded automatically.

Now the problems start..

I downloaded the Macphun Aurora and Luminar Software; I launch as a plugin from Lightroom, edit in the pop up window but when I click apply get an error message saying the image cannot be saved and my work is lost.

I downloaded the Nik 2018 software trial version, but whilst I can launch the plug in from photoshop, when I launch from Lightroom I get an error message saying that

I would be grateful if anyone can advise what I am doing wrong?

Thanks

JDL