"an online connection could not be established"

This is sad news. If I am not wrong during installation there is also a possibility of Manual Dial up or something such as offline activation. Did you try that yet?

Anyway if you still want to use internet in that case try to clear internet browser's history and cookies. Restart computer re-try your installation of Music Maker and during this do not run any other software, emial etc.

If your computer got any kind of Anti virus software it is better to turn off temporarily. Some time lowering Firewall (if any) could be useful too.

In the meantime you should also contact Magix support for the help.

nihon94