Okay, update.
The Exile 0.9.6 RC2 download removes the above 'keys error' (overlooked that folder), however when I enter the password and try to connect, I just get booted back to the server browser, via the Virtual Reality screen, with no error messages.
Tried launching Arma with and without @Exile and @Namalsk loaded, but same problems.
Edit: My RPT file from AppData/Local/Arma 3 shows the following (added a snippet) -
22:19:57 SimulWeather - Cloud Renderer - noise texture file is not specified!
22:20:13 Missing addons detected:
22:20:13 namalsk
22:20:16 Starting mission:
22:20:16 Mission file: ExileIntro
22:20:16 Mission world: VR
Namalsk has been added to my Arma 3 directory, so not sure what the error is telling me.