Thanks for the question. We haven't evaluated compatibility with Ubuntu 20.04 yet, but will certainly do that since it's a LTS version of Ubuntu server.
The currently supported OS list is available on our System Requirements doc, along with the hardware requirements and other notes.
I'll do some troubleshooting to see whether I can reproduce the issue you had with posting the comment, and advise our web group with any problems I see.
If you can reproduce the error, please send a screenshot which shows the URL to email@example.com.