Primary support is for 64-bit Intel-based Macs running OSX 10.6 or newer.
There is very little support for getting the background libraries and applications installed on OSX 10.5 or earlier, nor 32-bit Intel or any PPC, though all of these should be possible. GNU Radio has been compiled and installed on OSX 10.4 ("Tiger") through 10.15 ("Catalina") running any compatible version of Xcode on all recent and many older Macs - whether Intel or PowerPC/PPC.
Note V5.2 has been tested on Mojave and Catalina as a 64-bit application. If this does not happen, please re-read the instructions on installing XQuartz above. When the program starts, the first noticeable item should be that XQuartz starts up (icon in the runbar). Press that button, and XTrackCAD should now be able to be started without issue. (To enable it you may first need to click on the lock icon at the bottom of the window and sign in).