Well, the title of your linked article is already telling you that this is setting up unbound for encypted DNS.
Currently, you can either have recursion or encryption, see e.g. Unbound recursive DNS over TLS - #2 by Bucking_Horn.
This and other aspects of using unbound or encrypted DNS in conjunction with Pi-hole have been discussed here quite a few times, e.g. Best secure and privacy options for DNS.
You may use the forums search function to retrieve those. 