You can look into one of the factory methods and see what “context” is used for. I never needed it, so I didn’t look into it.
It is parsed by UTextureFactory::CreateBinary().
I think I mentioned several times in other discussions that “UnFbx::FFbxImporter::ImportTexture” (located in FbxMaterialImport.cpp) shows you how to do that.
I think you’ve been asking same questions few weeks ago and were given same answers. Code that is related to FbxImport and SpeedTree import shows how to import textures and even create materials. Did you look into that?