WD Invite to join NAS not working

I have sent my daughter in the US an invite to access my MyCloud EX2 Ultra server and she says that the email she got lets her access the mycloud web page but when she tries to input her email and password (the one that mycloud EX2 Ultra sent her) the SIGN IN button becomes greyed out and she can’t log in. I have removed her details from my Ultra EX2 and re-instated her with a new password but that still doesn’t work.She is using a macbook pro and her version is Yosemite or later.
I have recently updated to OS5 but this issue also happened with OS3. Does anyone have the same issue or is it just me. I have started a support ticket with WD but they are useless they closed the ticket without even notifying me one way or the other. Does anyone have any ideas what might be wrong.

The password for the web app doesn’t meet the criteria for password.