I apologize for any confusion this Help Center Article may have caused! This article is based on an updated version of the Contacts Tab that is not yet available in your account. This update is still currently in Beta as mentioned in the title of your linked article. Because of this, I would suggest following the steps listed in this Add, View, and Manage Custom Fields article instead. Are you able to find and edit the custom fields associated with an individual contact following these steps?
Frankie P. Community & Social Media Support
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