MacOs Catalina version 10.15.5

I assume that you are speaking about the older 32 bit apps which no longer can be opened under Catalina. We have been told by apple for years that a future upgrade was coming which would no longer work with any 32 bit apps. Now has occurred. Basically, if any apps allow for free upgrading to 64 bit operation, then download those newer upgrades. However, many apps such as those in Microsoft Office have also been upgraded (as opposed to updated) and now we must pay for the newer versions. You will have to visit the web site of each app to see what choices they offer.

By checking with the companies who make them and see if they have newer versions or updates;