After you approve a “messaging on behalf of” request, you will need to verify your business in Business Manager. WhatsApp uses this process to validate the true identity of a business.
Within Business Manager, click Business Settings.
Click Security Center.
Below Verification, click Start Verification.
Note: “Start Verification” is disabled until you approve the “messaging on behalf of” request from IMImobile.
After your business is verified, IMImobile will have access to message on behalf of your business and move on to setting up your number.