Good catch @Laura Paris!
I can't say for sure without more details but, my guess is it has just created an Atlassian account for you behind the scenes without you noticing, has copied your HC user details (name, title, password, etc.) over to Aa, and now is linking them for you. The purpose of doing it this way as far as I know, was to make Atlassian account a transparent and seamless part of your Atlassian experience.
...from the beginning. We have built up a lot of content in HipChat, with it being a core tool in our distributed company model. While it is true that we didn’t need to move to Slack immediately, we felt it...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs