Hi @Laura Low
Welcome to our forum!
As far as I know, to create a shared library, you'll need to sign in to the OneDrive site with your work or school account. However, shared mailboxes are not designed for anyone who shares a mailbox to log in directly to their account. The account for the shared mailbox itself should remain disabled. More information, see: Open and use a shared mailbox in Outlook.
Therefore, I would suggest that you can move files directly from Google Drive to OneDrive. For more details, please refer to: Migrate Google files to Microsoft 365 for business with Migration Manager.
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