Make sure that your Flow is working and set your Entry Point to Active.
Make sure your ad is set up and working in Ads Manager.
My Facebook ad is working fine, but it still doesn't appear
Check Ad placement
In the Placements section, make sure that:
you only have one placement for the Ad
the image hasn't been cropped
Check Ad permissions
Facebook is rather strict when it comes to permissions. So please check the ad permissions, in compliance with your page type. Here's how to check the permissions:
For a business account:
For a non-business account: