Why are you installing the DirectX (9.0c) June 2010 SDK?
AppGameKit doesn't use DirectX... at all.
There is a guide (pdf) within the Tier 2 SDK that explains what Folders you need to associate with a Project., and the Template Projects will have this already done for the Default Install Location (C:\Program Files (x86)\The Game Creators\AppGameKit Studio\Tier 2 and C:\Program Files (x86)\The Game Creators\AppGameKit\Tier 2)
You'll find the Templates in the Tutorials Folder.
Visual Studio (Community | Professional) will automatically install the correct Build Tools and Windows SDK., but for other platforms you'll need something like Xamarin installed.
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If on the other hand you're building the Dark BASIC Professional 1.07.2 (GameGuru) Source., then you will need a DirectX 9 SDK... but it's actually quite a specific one.
Believe it's August 2009., otherwise you'll be spending quite a quite editing A LOT of the Source to be compatible.