The DUNS Number is a business code used for international trading and transactions that occur internationally. If you do not have a DUNS number, Apple can generate one for you, free of charge. Please visit the following link to acquire or learn more about the DUNS Number.
After completing and requesting the number, you will eventually receive an email confirming the process. This process takes several days, so be aware of communication from Apple via email.
The DUNS Number is required to open business account with Apple, so this is a requirement to further develop the mobile app.
You will need to find a link in blue that will take you to a “DUNS Number Lookup” after logging in with your Apple ID.
Click here : DUNS Look up tool
Don’t have an Apple ID? Please register for a New Apple ID
Access the site: http://appleid.apple.com. Make sure the “country” is set to the United States, this makes it easier to register.
Then click "Create an Apple ID" and follow the next steps. Fill in all the data. The Apple ID must be a valid email address (within 5 business days according to Apple confirmed later).