Apple has made it clear for the past two years 32 bit software (such as Office 2011) would be dead. That has now happened in Catalina. You were warned of this for the same past two years. Every 32 bit app you opened would produce a popup telling you xxx was not optimized for your system and would not run in a future OS.
MS also considers Office 2011 dead. They dropped all support for it last October. That you paid for it is meaningless. You pay for a car, too, but don't expect it to last 500 years, do you?
Software companies cannot stay in business by having users purchase something once and then keep that software going for free in perpetuity. They stay in business, so they can pay their employees and other bills, by having you buy new versions.
You can purchase the subscription Office 365, or the one-time cost Office 2019 as a replacement. This, if you need to stay specifically with Office. Otherwise, there's the free open source OpenOffice or LibreOffice. Neither has a replacement for Outlook if you need that.