RootsMagic 7 can run on macOS but it is not a native application of macOS. As per RootsMagic 7, They use a wrapper which is provided by Codeweavers. It is a crossover of software and they use 32bit. This is the reason; you will not be able to run RootsMagic 7 on Catalina macOS. As per the RootsMagic blog, the CodeWeavers are working on a 64bit application and soon you will get updates that may allow you to use the software on the new macOS 10.15.