Family member cannot join custom email domain via iCloud+
I have an iCould+ account through the Apple One subscription. After creating a setting up my custom domain as the account owner, I sent a request to add a member to the custom domain.
From this point that invite was never sent, the invitee never recieved a notice of being added to the domain, nothing. Then when I would remove then as a member from my phone, they get a message on their devices saying they had been removed.
More over, this invitee could not see the iCould+ option for Custom Email Domain in their settings, even though my phone showed them as a member of the custom domain.
What is the problem?
iPhone 14 Pro