Welcome back.
I think there's a misalignment of expectations or a confusion here.
Lubuntu is an independent Linux distribution currently not officially supported by Centrify Express
This means that we don't actively test our software and utilities like installers, CLI utilities and add-ons.
The Express download page explicitly names the distributions and versions supported by Centrify.
Since Lubuntu is a Debian derivative, it is possible to install CentrifyDC, however at that point you are on your own the same way our software works with newer OS versions.
For example. Today (1/9/16) I read that Red Hat has made available the beta version of RHEL 6.9. Although it's possible for our software to "just work" if Red Hat did not make major changes, users are still on their own. We have an SLA of 6 months to provide full support.
You should go to th e Idea Exchange and request that we add support for the platform, however only a significant number of commercial customers moves the needle when new platform support is considered.
A big example is different OSs using the POWER8 little endian. We had many commercial customers request support for it and we are adding these in Suite 2017.
I hope this clarifies the confusion. As always we are here to help and open to feedback.
R.P