A Microsoft file hosting and synchronization service.
Hello, thank you for reaching out to Microsoft Q&A.
Try this workaround:
https://account.microsoft.com/services
Sign in to the Microsoft account using the Family Organizer account on the link above, turn off auto-renewal (Recurring payment) for the Office 365 subscription, wait an hour or two, and then turn auto-renewal back on. This may enable the 1 TB of storage for all family users shared under the subscription.
This workaround has helped several users before, so please see whether it works for you as well.