Hello jasonhd ,
Can you let me know what version of the toolbox you are using? You can find it easily by looking into Add-on Manager from MATLAB or by running the following command:
ver
If you want to use the default compiler (gcc), it already comes shipped with our toolbox; if you don't have any environment variable defined, the toolbox will automatically set it up for you to the gcc we ship.
As for the variable, you can set it in windows or in MATLAB; but if you choose the 2nd option, you should set it every time you open MATLAB.
As for the error, can you attach the model you are building so we can test it on our end?
One more thing I want to mention is that it is recommended you install the toolbox in a path with no spaces.
Kind regards,
Razvan.