To download older releases of MATLAB, please go to the following link:
After signing in with your MathWorks account, you will be directed to the Downloads page. In the "Download earlier release" section, scroll down to almost the bottom and select "R14SP3". Choose a supported platform according to your machine. In the product list, choose the products you are interested in (MATLAB, MATLAB Compiler, and MATLAB Report Generator) to download, and you are all set.