About linking WhatsApp Business with Facebook and Instagram
To give your customers another way to communicate with your business, you can link your WhatsApp Business account with a Facebook Page and/or Instagram Profile. When you link your Facebook Page or Instagram Profile with your WhatsApp Business account, your number appears as a contact option on the linked Facebook Page and/or Instagram Profile. When a customer taps on this contact option, they can message you directly on WhatsApp.
Once linked, your Facebook Page automatically syncs business information to your WhatsApp Business account.