Unable to complete transition to MyCloud 5

Hi, I am new to this group, but am hopeful I can get some help. I am attempting to transition to WDMycloud 5 (from 3). For background, I think the upgrade completed, When I log in to the NAS using my admin credentials, I can see the firmware is updated to 5.18.117. I can access NAS data from my Window PC. I can also see a new user I created since the upgrade.
I am now trying to turn on the cloud access so I can access data remotely from my iPhone. The problem comes when trying to log into MyCloud 5 using my email address. I get and email saying there is a Suspicious Login Attempt. The “click here” link in the email gives me an “Authentication Error” & “This URL can be used only once” dialog box. The system log shows a SAMBA error “authentification for user (admin) has failed”. When creating my MyCloud 5 account I don’t think it was successful. Any help is appreciated.

The following WD Knowledge Base Article may be relevant.

My Cloud OS 5: Something Went Wrong - Suspicious Login Attempt Email Notice