Enabling Google AMP ads on an AMP page is relatively simple. You will need to place the appropriate AMP ad code on the page. Here is the list of things you need to know:
Sample Google AMP Ad Code
The code below is a sample that would be used for the Taboola ad network.
<amp-embed width=400 height=300
data-placement="Below Article Thumbnails">
Other Google AMP Ad Considerations
It is very likely that if you are using a WordPress Google AMP plugin to support your AMP pages, that it will not properly support your ad code. You may need a customized plugin to get the desired ad implementation.