The Mac OS version of ECHO3D has no GUI or viewer. Hence I would start with the windows version and only after some experience to switch to the Mac OS one.
There are my instructions how to use ECHO3D under Mac OS.
1. Download it from the site “echo4d.de”. It could take some time to wait before the download will start.
2. I am not registered Apple developer. Hence by the first run you have to confirm that you trust the executables. In Finder go to the directory “Codes/Mac” and make a right mouse click on “ECHO3D” executable. Choose “Open” in the drop down menu and then choose “Open” in the dialog again. The program will start in a terminal window. Close it. Make the same for the other three executables in this directory.
3. Go to “Examples/N1_RoundStepOut_LongWake” and make a right mouse click on “run_Mac.command” script. Choose “Open” in the drop down menu and then choose “Open” in the dialog again. Now all 4 programs will start in the sequence and the calculation should be successful.
4. Go to directory “Post-processor” and start script “PP_LongitudinalWake.m” in Matlab.Otherwise it should be easy to convert the Matlab scripts to Python.
5. The examples are described in “ECHO3D examples manual.pdf” which can be found in directory “Docs”. In the same directory there is a common manual for all ECHO codes.
Thank you for the interest and write me if any difficulties or bugs appear.