At this stage of development the recommended way to run Kolibri on Linux is to use the PEX file, same as for macOS. There is a DEB installer on Launchpad, but it is still Work-in-Progress and it might create other issues. We recommend you download the PEX file to test this latest release of Kolibri.
When you run Kolibri 0.7 from the PEX file, you will be able to import content from public channels without knowing the channel ID/token in advance, which was required in previous Kolibri versions. Go to Device > Content, press the Import button, and (if the device is connected to Internet) you will be able to select a channel to import from those available on Kolibri Studio site, that is the “Kolibri Central Server”:
If you have curated a content channel of your own on Kolibri Studio, you will have to know its ID/token and use it to import its content into Kolibri. Scroll at the bottom of the public channels in the above step, and use the Don’t see your channel listed? Try adding the token link at the end.
As for the Note 2, it’s more of the warning then error, and as you noted Kolibri runs correctly despite it. We will work on making that terminal message less confounding for the users.