Hello lohrsistemas,
The build button does not appear because you probably don't have a license for Simulink Coder.
I must mention that even though our toolbox is free of charge, you will be needing some licenses from MATLAB (for Simulink Coder, Embedded Coder, Stateflow, MATLAB Coder). I see that you're using a trial license for Simulink - you could probably get a trial license for all those I mentioned and check out our toolbox.
Hope this helps,
Razvan.