How to manually insert Zaraz code into several parts of HTML?

I’m testing Zaraz instead of Rocket Loader (I thought Zaraz is much safer) to speed up loading third party scripts on client sites. The site has really a lot of calls for external domains, which is causing the site to load slower.

There’re several different ad codes for different sections of a page, like one for before sub header, one for sidebar top, etc…I’ve read the document, and figured that I need to insert global code into section. But I can’t find any explanation of how Zaraz would figure out where exactly the ad code should be inserted within HTML.

So I set up like this in Zaraz using custom HTML.

googletag.cmd.push(function() { googletag.display('div-gpt-ad-1591325772350-0'); });

then on the site (WP), I also insert the same tag, will Zaraz replace, so the ideal code gets triggered at the ideal ad placement?

How do others use Zaraz to control diferent types of ad sizes and ad placements?