My apologies, I think there was a misunderstanding that this had been resolved over email.
From what I understand from the link you posted that you were looking to update your authentication settings. It looks like the URL should have taken you to the settings listed under My Account (accessed by clicking your name in the upper right corner of your account navigation bar) > Advanced Settings > Add Self-Authentication.
Is that the menu you were looking for? This article should have the instructions with screenshots which may be easier to follow.
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