I don’t know if you can see the latest Version on the app store and you did not give the version (date) of the one you now have installed. There can also be other reasons why it’s not working but having the current version running is a must have for the current version of Roon (build 846).
I don’t know what you are talking about. It might help to post screenshots.
You already have the latest Roon Server application running, that’s why you need to install the latest RoonServer app for QNAP NAS too. Looks like the current version is not available from RoonOnNAS.org currently but I found this message from the package maintainer:
How to manually install packages in QNAP is described here: