neilday: Unfortunately, only Darkfall installed. Aura gave me the message "internal error" during installation and stopped and Black Mirror triggered Avira and sent one of the files to quarantine during install. I emailed JA for a help and they sent me to this thread, but so far there's been no discussion about installation problems.
JustAdventure support redirects You to a thread on gog for help? That's some support...
Haven't tried Aura yet, but I installed Black Mirror without issues. That Avira quarantine is probably just a false positive, try adding whatever bugs it to the exceptions.
I did have some problems with downloading the Dark Fall installer though, the download seems to have been interrupted a couple of times - once it 'almost' made it, and the installer would launch but give some errors later. Finished fine finally after the third try. Maybe that's the problem You're having with Aura? Have You tried re-downloading the installer?
And finishing the DRM report, "Dark Fall Lights Out DC" seems to be DRM-free.