Office 365 Shared Mailbox without 365 License

I can get a shared 365 account with a license to work by the information given here but my shared mailboxes that don’t have a license will not display when I search for them. Has anyone achieved this? Can this be done?

Office 365 Shared mailbox - Mail - eM Client

From Microsoft 365 admin center help:
Licenses: Your shared mailbox can store up to 50GB of data without you assigning a license to it