D-Link Switch: username and password?

I would like to use a D-Link Switch but I don’t understand to which username and password the documentation referes to.

straight from the documentation

username
(string)(Required)

The username for your plug.

Default value:

admin

password
(string)(Required)

The password for your plug.

Default value:

The default password is the PIN included on the configuration card.

I tried that and it didn’t work. But after investigating more now I see that the device appears in the modem network’s page with its fixed IP, but I can’t ping it (while I can ping other devices in the network).
It works properly with the mydlink app, so it’s properly connected to the local network and to the internet.

So I think this issue of being unreachable by a ping prevents it to be connected to the Home Assistant integration.

A device that doesn’t respond to a ping is most likely not there. It’s probably a different address.