I tried to join this instance today, but never received the conformation email. When I tried to register, it said my email was already in use (for the first time I'm guessing).
Try if you can login using your username and
your password, then check in settings if you
mistyped your email, if so, change it to verify
your email again.
This method works about few months ago when I create my new account on other instance, don't know if this still works.
Also, as other mentioned - check your spam folder.
Okay, thanks for pointing out. May be you can try to use a different email address, or using a plus address (helfrd0771+lemmy[at]gmail[dot]com in your case) if you want to use the same username.