Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi Hobbsy1618,
However, we recommend for Office 365 best experience use Office 2016. You can access the shared mailbox by using Outlook 2016: For your reference: https://support.office.com/en-us/article/Open-and-use-a-shared-mailbox-in-Outlook-2016-and-Outlook-2013-d94a8e9e-21f1-4240-808b-de9c9c088afd
Moreover, you may contact our dedicated Apps on Windows 10 support to see whether they can provide any alternative solution or workaround. Your time and understanding will be highly appreciated.
Best regards,
Shyamal