Ads not showing in Instant Articles

Hello! I installed this plugin by recommendation of a friend, after unsuccessfully trying a couple other ones. It seems to work fine and displays Instant Articles with no problems. However, I’m not able to get ads from Facebook Network Audience to show up.

I have been admitted into the program, I have created 2 ads (“placements” as they call them), I have copied their IDs into the plug-in form setup and I have enabled the “Activate automatic placement of ads for Instant Articles” options. What am I doing wrong? Is there anything left I should do and haven’t done?

Thanks!