To set up the Facebook Lead Ads endpoint, you need to have a developer account and create or already have an app.
Note: Facebook provides the most up-to-date and detailed setup instructions at https://developers.facebook.com/docs/apps/register.
To create an app:
Create a new Facebook app.
Note: The Add App button is located in several places, but an easy way to get to it is from your menu at the the top of any Facebook for developers page:
Complete the Create a New App ID form.
Click Create App ID.
On the Product Setup page, locate Marketing API, and then click Get Started to complete the Marketing API setup for Facebook Lead Ads.
Set up the app's platform as a website: Go to Basic Settings, click +Add Platform, and then click Website. .
For OAuth authentication, add the Facebook Login product: click + Add Product, find Facebook Login at the top, and then click Get Started.
In Valid OAuth redirect URIs, enter your oauth.callback.url
.
Click Save Changes.
Once you are ready to release to production, you will need to submit your app for testing. You can read more about the process at: https://developers.facebook.com/docs/facebook-login/review/requirements
Next create an instance.