Donald,
The VSL you are noting in your question has to do directly with the AudioBox VSL series of interfaces and their software controller. This is completely separate from the software for the StudioLive Mixers.
If you take a look back at the article that you are referencing:
http://support.presonus.com/hc/en-us/articles/214029543-Universal-Control-1-8-1-Release-Information
You will also see a very important notion:
It is important to remember that Universal Control 1.7.4 was the last UC version that supports Gen 1 StudioLive Mixers and FireStudio interfaces. UC 1.8.1 does not support the classic mixers and interfaces.
In order to use a classic StudioLive Mixer you would need to be running the UC Version 1.7.4; as listed above. Additionally, you will never get any audio in UC 1.8+ when running it in DEMO Mode. The DEMO Mode is just what it is labled. Its a Demonstration of the UC Control software for the newer AI Mixers vs actually running the UC control software with a live mixer; which would be routing audio into the computer and then would be showing signal levels.