I noticed that you are using an older version of PowerShell 1.0 to connect to the Exchange online PowerShell module .
I wonder what version of the Exchange online connect-exchangeonline you are reminded to connect to when you run PowerShell module?
Is it a V3 version?
If you can, we recommend that you update your version of Windows PowerShell to the latest version, try connecting to Exchange Online PowerShell again and use this command to create a shared mailbox to see if there are any changes.
Here's a guide to updating Windows PowerShell for your reference:
Update PowerShell to the Latest Version - Active Directory Pro
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