How do I update OFFICE Mac, I thought I updated it already

Your question is confusing. Normally one would update an app to be compatible with a new operating system not the other way around. Please rephrase your question to indicate what you currently have and what you are wanting to do.

I'll take a guess that you upgraded your computer to Catalina and now your old Microsoft Office no longer works. If this is the case then you will need to upgrade Office. Microsoft Office 2016 (updated), Office 2019, and Office 365 all work with Catalina. Microsoft Office is available from Microsoft.