Before you can create a WhatsApp Business Account you need to make sure that your Facebook Business Account is verified. You'll need to be a Admin of your page to do this.
If your Facebook Business Account is already verified, you can skip to Step 2.
Within your Facebook Business Manager go the Security Center and click 'start verification' in the Business Verification section.
Enter your business details and click next.
Select the correct business from the list. If none are applicable, select None of these match.
Confirm your business details.
Choose to receive a a verification code by either text, phone or email.
Enter your verification code.
Click Submit.
If you receive a confirmation that your business is verified, you are all set to create your WhatsApp Business Account and move to Step 2. You'll receive a notification in your Business Manager once the verification is complete.
Step 2 - Create your WhatsApp Business Account from Quickdialog
Once your Facebook Business Account is verified, you can create your WhatsApp Business Account directly from the Quickdialog interface.
Go to Configuration -> WhatsApp -> and click on the Add icon.