I try to maintain compatibility with two versions of macOS for a given version of RAW Power.
So, RAW Power 3.0 will run on Mojave and Catalina, but not High Sierra. At some point, RAW Power only run on Catalina and Catalina + 1.
However, note that features like Photos library support are only available on Catalina, so you would not be able to use that when running RAW Power 3 on Mojave.