Here are the steps you need to follow to add the WhatsApp button to your Instagram profile:
Go to the Instagram profile page and click on Edit profile;
Click on Contact options;
In this section you can enter your contact information, such as e-mail, telephone number, address and, recently, also WhatsApp;
Click on WhatsApp;
Here you need to enter the number associated with WhatsApp, to which the verification code will be sent;
Enter the verification code in the Instagram profile.
At this point, the new WhatsApp button should appear, which will allow all visitors of your Instagram profile to contact your company with a single click. Remember that you can always manage all messages from your social networks, like Instagram, Facebook, Whatsapp or Telegram via Callbell.