I found this information in an earlier post (2013)
The versions on the A6 which do not have nav have the smaller monochrome red screen and four function buttons on the MMI control instead of eight (it will have radio, media, tel, car but missing nav, directory, setup and info. They are also missing the navigation module in the boot. Personally, I find a TomTom does just as good job but the updates cost a fraction of the price! It just doesn't have the 'built in' feel.
I know it doesn't answer your question as to how to work the system but it does seem as though it is now considered old school technology and probably not worth bothering to update, etc.