Office versions and connectivity to Microsoft 365 services

From October 13, 2020 onward, only these versions of Office are supported for connecting to Microsoft 365 (and Office 365) services:

• Microsoft 365 Apps for enterprise (previously named Office 365 ProPlus)
• Microsoft 365 Apps for business (previously named Office 365 Business)
• Office LTSC 2021, such as Office LTSC Professional Plus 2021
• Office 2019, such as Office Professional Plus 2019
• Office 2016, such as Office Standard 2016

Examples of Microsoft 365 services include Exchange Online, SharePoint Online, and OneDrive for Business.

For Microsoft 365 Apps, you must be using a supported version. For a list of which versions are currently supported, see Update history for Microsoft 365 Apps.

Ref: 

https://docs.microsoft.com/en-us/deployoffice/endofsupport/microsoft-365-services-connectivity