Adding WhatsApp button on Facebook
To add a quick WhatsApp button or/and to run WhatsApp Ads on Meta you have to request to connect a Facebook Page with the WhatsApp Business Platform phone number.
After the connection is complete, you can add a button to your Facebook Page and create ads that let customers send you messages directly on WhatsApp. Customers can start a conversation with you on WhatsApp when they click the Send message button on your Facebook or Instagram ads.
Make sure that you use a WhatsApp Business Platform phone number to connect to your Facebook Page. The connected phone number will be shown to anyone who sends you a message through the button on your channels.
To request to connect your Facebook Page with the WhatsApp Business Platform phone number:
Navigate to your Facebook Page.
Click Settings.
In the left side column, click WhatsApp.
Note: You can only find WhatsApp in the Facebook Page for your business. You can't find WhatsApp in your personal Facebook profile.
Choose your country code and enter your WhatsApp Business Platform phone number.
Click Continue.
You can now see the status of your connection request.
You'll be notified when your request is approved or declined. If the connection is approved, your Facebook Page will be connected with the WhatsApp Business Platform account.
You can see the connected phone number in the Settings tab of your Facebook Page. You can add a Send Message button to your Facebook or Instagram ads. When your customers click the button, it'll start a conversation thread on WhatsApp where your customers can connect with you.