I have a script and div tag from amazon to put ads on my site but when I put them in my app the ads do not show up.

The code from amazon looks like this:

<div id="amzn-assoc-ad-xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"></div>
<script async src="//z-na.amazon-adsystem.com/widgets/onejs? 
MarketPlace=US&adInstanceId=xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"></script>

I have tried adding the

<script async src="//z-na.amazon-adsystem.com/widgets/onejs? 
MarketPlace=US&adInstanceId=xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"></script>

to the index.html file as well as something like this

useEffect(() => {
 const script = document.createElement("script");

 script.src = "//z-na.amazon-adsystem.com/widgets/onejs? 
 MarketPlace=US&adInstanceId=xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
 script.async = true;

 document.body.appendChild(script);
}, []);

The <div tag is in the return of my functional component, but no ads show up. Any help is very appreciated.