How do I get my Mozilla/Firefox Add-ons account back?

When I try to login to my old Add-ons account I get the message ‘unknown account’.

I still have the confirmation email from 2009.
I can even see my userpage:

But I can’t recover my account.

I created a new firefox account with the same email address because someone said it would link the accounts, but nope. It just created a new add-ons account with gibberish at the end of the URL.

I’ve been out of the Firefox loop for several years so it’s irritating that this would happen when I’m tempted to consider using the browser again.

I can’t figure out how to delete or close this. Mark has since helped me resolve the issue. Thanks again.