So it looks like setup on ubuntu should be pretty straightforward. Follow these steps to install the java client as a package: https://geti2p.net/en/download/debian
Then under their Post-install work on the bottom of that page follow this:
as a service that automatically runs when your system boots, even before logging in. The service can be enabled with "dpkg-reconfigure i2p" as root or using sudo. This is the recommended means of operation.
That will cause i2p to automatically run at startup. You can use the other methods there if you don't want that behavior. Lastly, you'll need to configure a browser to use i2p. https://geti2p.net/en/about/browser-config
Firefox is a good one to use for it but you can use librewolf or another one.
And I think that's it as far as setup for ubuntu. Let me know if you have more questions : )
Hey OP, a lot of people are suggesting psilocybin or other psychedelics. If you're interested you can ask questions about that in the !magic@wizanons.dev community. I moderate it but there are psychonauts there that know about this stuff who are friendly and helpful.