I am glad you brought up this topic because i faced the same obstacle a few weeks back when i was trying to onboard someone.
Hive kept saying out of tickets and all that stuff.
So i had to use ecency to sign up firstly and it opened but we still had to sign up properly with hive to get her keys.
What i was that i logged out my account and tried logging in her own which they now requested she should download her keys and i did that immediately.
Keys were downloaded and i used it to log in properly on hive.io
That was how i faced that challenge.