I was trying out this plugin but wasn't unable to get it running - till I found out that in the website configuration I try to track to, I must uncheck this

or must include "http://demo-anonymous.matomo.org" too, otherwise, the tracking didn't work.
Is this a relic from the past when usage data was optionally sent to matomo.org? Is it a bug? Or am I overlooking something obvious?
Thanks in advance for your help and work!