While the AWA portion of the MGMAT CATs reflects the real CATs, they are not the questions that you will actually be asked on the GMAT. The software that you downloaded is created by the GMAC and is as close to the actual AWA section of your test as you can get. You are therefore asked actual retired AWA essay questions and you're graded accordingly.
Unfortunately, therefore, you cannot use this program to grade the AWA questions you answered in our CATs. You can however, still use the program to grade the two new essays it prompts you for.