Please follow the steps in the doc you linked, if you create an email in HivePress/Emails and assign it to the Listing Approved event, then this custom email you added will override the default one.
Once you save this custom email, please check the listed tokens in the description, you can use any of these tokens in the email subject or text. For example:
Once you select the email Event and save changes, please check a list of the available tokens below Screenshot by Lightshot For object-like tokens like listing or user you can access any of their attributes this way: