This is a reminder as this has been announced in September 2019 (https://www.microsoft.com/microsoft-365/blog/2017/04/20/office-365-proplus-updates/), Office 2013 clients will no longer be supported to access Office 365 services (Exchange Online, SharePoint Online or OneDrive for Business) starting October 13th 2020.
If you are still using Office 2013 clients to access Office 365 services you have to plan as soon as possible to upgrade to either Office perpetual in mainstream support (aka Office 2016 or 2019) or Office 365 Pro Plus.
If you are not sure, you can use the SCCM Product Lifecycle dashboard (Assets and ComplianceOverviewAsset IntelligenceProduct Lifecycle) or the Office 365 ProPlus Upgrade Readiness report on the Office 365 client management (Software LibraryOverviewOffice 365 Client ManagementOffice 365 Proplus Upgrade Readiness)
You need to ensure you have enabled the Hardware InventoryOffice 365 ProPlus Configurations class on the client settings.