Hello,
I just created an account, then I filled in the form to get a URL (mysitename.atlassian.net).
When I log in, I get the following message: The administrator rejected your request. How to log in and test/use Jira Work Management.
Thank you in advance
Hello, I am the person who created the site! So I don't understand why it's impossible for me to connect to it.
You have given admin rights to someone else, who has now locked you out of it. Or, you have let the site lapse (no one logged into it for a few months, so Atlassian have shut it down).
Either way, start by going to admin.atlassian.com and having a look at what products you have (it'll tell you where they are) and what access you have to them.