In order to use MWClient’s MATLAB interface window, you need to tell MWorks the location of your MATLAB installation. To do this, you must create a symbolic link named MATLAB in the Applications directory that points to the MATLAB application.
For example, if you’re using MATLAB R2020b, open Terminal.app (in /Applications/Utilities) and type the following:
cd /Applications
ln -s MATLAB_R2020b.app MATLAB
If MWClient is running, quit and re-open it for the change to take effect.
Note that you don’t need to recreate the symbolic link if you upgrade MWorks. However, you do need to repeat this procedure if you want to use a different version of MATLAB.