Those instructions advise you to use the current supported LTS release of Ubuntu Server which is 20.04.
It means that in 9 months from now, Ubuntu will not release any security updates for this version, leaving security issues unpatched after July 2021. So before that happens, you should have moved away from 20.10.
Ubuntu 20.04 will get security releases until April 2025.
See Ubuntu release cycle | Ubuntu
Yes, that’s safe to say.
without any problem = without Ubuntu support related problems
in the future = until April 2025