Hi again Barry,
the MegaGames are designed to run on both, Mac (requirements: Classic Mode or OS X, 120 MHz PowerPC,32 MB RAM) and PC, so I would recommend that you delete all previous download attempts and start fresh again. Before you download the Mega Games please ensure that you have Stuffit Expander installed in your computer, as you will need this program to complete the installation. You can download Stuffit for free via the following link:
Once you download the MegaGerman Installer again, you will see a folder called megagerman.zip. Extract the folder using Stuffit Expander.
Once all the contents of the folder are extracted, you should see a few different files inside the MegaGerman folder. Click on the file with the Rocket German icon (RocketGerman.exe) to run the MegaGames.
If you are still having problems, please let me know.