Hopefully you will already be aware of the details I'm going to post here for you since it seems you're already in the middle of your upgrade.
! Before you upgrade to Catalina, please look at these Apple Support documents. Specifically, check that your Macintosh is on the list of compatible computers and familiarize yourself with the limitations of 32-bit applications and Catalina.
How to upgrade to macOS Catalina – Apple Support
Learn about 32-bit app compatibility – Apple Support
Be aware that any 32-bit apps that you are currently using will be incompatible with Catalina and will not run. You must update to Catalina-compatible versions or replace them with alternative applications that meet Catalina’s 64-bit requirement.
This includes older versions of Adobe CC, Microsoft Office applications and many others. All current Apple software is Catalina-ready, and updates for some older Apple titles are available for download in the Mac App Store.
You can check which of your current apps are 32-bit by clicking Apple menu >System Preferences > About This Mac > System Report. Then scroll down the list on the left to <Software> and click <Applications> (you may have to click the triangle next to Software). It may take a moment, but shortly your Mac will display a list of the apps installed on your computer. You can then click the column labeled 64-Bit (Intel) and sort them by Yes/No.
Any apps that are listed as No in the 64-bit column will not work under Catalina.
This 32-bit detail has tripped up many users who have upgraded to Catalina and then find their software is broken.
Optionally, to check for 32-bit apps, you can use the free app Go64. – a compatibility scanner from St. Claire Software.
