Managed .NET plug-ins are built for a specific three-version window of AutoCAD, and while generally upwards compatible (I can run DLLs I built for AutoCAD 2008 in 2011) are rarely downwards compatible. Pre-2008 AutoCAD releases had very limited .NET support as well.

From the looks of the preview this has been built on the AutoCAD 2010/11/12 series.
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If you are going to fly by the seat of your pants, expect friction burns.