If you are an Application Service Provider (ASP) for Sinch Products, and you want to set up the Facebook Messenger channel on a Conversation API app for one of your customers, you must provide a way for your customer to connect their Facebook Page to the Conversation API app. You can do so by adding a Facebook Login button to your site. When you give a customer access to this button, they'll be able to provide the account information required to complete the configuration of the Facebook Messenger channel on the Conversation API app.
In order to add a Login button:
Learn more about the Facebook Messenger channel of the Conversation API.