Directly Through Facebook
For businesses to create a WhatsApp business profile, it comes with a tad bit of approvals. To enable the WhatsApp Business API for your business, submit your industry profile for consideration using this link:
https://www.facebook.com/business/m/whatsapp/business-api
To start with this, you need to sign up directly. Going with this process is somewhat technically challenging for small businesses.
For example, to set up WhatsApp business API, you need a developer even though you can get the entire process details on the Facebook official support pages.