Depends on what you mean by "Jira account", but assuming you mean "access to a specific Jira system", you will need to either
You need to contact the admins or owners and ask them, as you can't see a sign up.
I really cannot tell you more than that. Cloud alone has 125,000 separate Atlassian systems in use, and there are plenty of server/DC systems out there too. You have not told us which one(s) you want access to.