Paths in setup.py in /path/to/MATLAB_R2020a.app/extern/engines/python have to be configured manually.
The directory are not being recognised corretly by the setup script, find the lines with definition of _bin_dir and _engine_dir and replace them with absolute paths
_bin_dir = "/path/to/MATLAB_R2020a.app/bin"+os.sep
_engine_dir = "/path/to/MATLAB_R2020a.app/extern/engines/python"+os.sep\
+ "dist" + os.sep + _matlab_package + os.sep + _engine_package + os.sep