Hi @BernSzukalski , few things that prevent me from using map viewer for pop up configuration.
First off, it seems like a map service cannot be used for pop up configuration in map viewer - configure pop-ups is grayed out in the menu.
Also, even if I use a feature service, I don't have the html enable menu in my map viewer as per picture below. I can see the html menu in your blog but not in my one unfortunately. Is it because the enterprise version that I am using?