Translations:How do I get an account?/7/en

All you need to create an account is a username and a password. Depending on the instance and the software it is using, you might need an email address (some software like Mastodon force this requirement, but for others like Pleroma this is optional or configurable by the admin). Usually, no phone number or other form of identification is needed.
You can choose any username that doesn't exist on that instance yet.
So even if someone else on the Fediverse is already called @anonymous you can still call yourself @anonymous if you're on a different instance.