Share image on Instagram from Unity - http://u3d.as/1pMn

ShareImageOnInstagram.cs

using VoxelBusters.InstagramKit;

void ShareImage(string filePath)
{
    // Create Story Content Instance
    StoryContent content = new StoryContent(filePath, false);
    InstagramKitManager.Share(content, OnShareComplete);
}

private void OnShareComplete(bool success, string error)
{
	string message  =  success ? "Successfully Shared" : "Failed to share " + error;
	Debug.Log(message);
}