MS Office365 apps

The subscription is not platform specific.

If you subscribe to Office 365 Home, you get 6 licenses for Windows and MacOS. You can mix and match however you like.

If you have Office 365 personal, you only get one license.

If you have personal, It will be more cost effective to upgrade your subscription to Home instead.

You seems to be talking about Office 2011 applications. You need to upgrade to Office 365, and download the 64-bit versions from https://setup.office.com/?ms.officeurl=setup. Another option is to run old 32-bit apps like Office 2011 on Virtualbox for Mac. Here is the way to install macOS Mojave on Virtualbox running inside Catalina https://www.winytips.com/open-run-32-bit-apps-macos-catalina-fix-needs-be-updated-error/

If you're an Office 365 subscriber you can update them directly from Microsoft or just download the app store versions and sign in with your Office 365 account.

If you can't remember your account information for Office 365, you'll have to talk to Microsoft.

Office 365 is a paid subscription service. Are you sure you're a subscriber?

Look into the Free LibreOffice, it handles MS Office files…

https://www.libreoffice.org/