No response when trying to obtain the registration is a problem for quite a few new gmax users.
You can use this register
workaround to get gmax up and running.
As for tutorials and you being new to 3D design, start working through the official gmax tutorials. They will help you more than trying to start off by working through tutorials for building aircraft. You need to get the basics down first and learn some of the tools.
The official tutorials are good at teaching the GUI and most commonly used tools. More specific tutorials tend to assume you at least have a basic knowledge of gmax.
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