Hey, I also joined with my email, and later connected my keychain, so that should be possible for you too.
If you get an error message, you can shoot a support ticket on the website, they will help you further as soon as they can.
I used my hive username for easy reference...
and thanks for using my ref I saw your name in the list just now!
Oh cool. I am going to do that soon, If I encounter any more difficult, I'll hit you up or use the support as you adviced. Thanks alot. ❤️