Hi Nilakshan,
The error message "Undefined function or variable 'arduino" implies that the there is no Arduino support package currently installed.
Please use the below command to check if the support package is installed correctly,
which arduino -all
If the Arduino support package is installed succesfully the full path of the installation directory will be displayed, otherwise '''arduino' not found" message will be displayed.
To install the support package, please refer to the following MathWorks documentation: https://www.mathworks.com/help/matlab/supportpkg/intro.html#:~:text=and%20its%20peripherals.-,Install%2C%20Uninstall%2C%20and%20Update%20the%20Support%20Package,-Install%20the%20Support
Hope this helps!