From:https://developer.apple.com/support/D-U-N-S/
The D-U-N-S Number is a unique nine-digit number that identifies business entities on a location-specific basis. Assigned and maintained by Dun & Bradstreet (D&B), the D-U-N-S Number is widely used as a standard business identifier.
Your D-U-N-S Number will be used to check the identity and legal entity status of your organization as part of our enrollment verification process for joining the Apple Developer Program or the Apple Developer Enterprise Program. While many types of businesses can receive a D-U-N-S Number, your business must be recognized as a legal entity (e.g., a corporation, limited partnership, limited liability company) to enter into the legal terms and obligations of Apple Developer Program agreements. DBAs, Fictitious Businesses, Trade names, and branches are not accepted.
Companies and educational institutions must provide a D-U-N-S Number registered to their legal entity, while a D-U-N-S Number is optional for government organizations. If you are enrolling as an individual, you do not need a D-U-N-S Number.
D&B may have already assigned your organization a free D-U-N-S Number. Before enrolling, use theD-U-N-S Number look up tool to see if you have one. If your company is not listed, you'll have the option to submit your information to Dun & Bradstreet for a free D-U-N-S Number.
You will be asked for the following information when requesting a D-U-N-S Number using theD-U-N-S Number look up tool:
As part of their verification process, a D&B representative may contact you directly for more information (e.g., type of business, number of employees). Please have your business registration documents ready.
After requesting a D-U-N-S Number, please allow up to 5 business days to receive your number from D&B. Expediting your D-U-N-S Number creation process will not shorten this waiting period. If your application has taken longer than two weeks to process, please email D&B.
Once you receive your D-U-N-S Number, please allow up to 2 business days for Apple to receive your information from D&B. After this period, you may enroll as a company/organization in the Apple Developer Program.
To update your D&B profile, please email D&B. It takes up to 14 business days for D&B to provide updated information to Apple.
The business you entered is either listed in the D&B database with a different legal status (e.g., sole proprietorship), or its legal status has not been verified. When enrolling, make sure to use the legal entity name of your organization, as Apple does not accept DBAs, Fictitious Businesses, Trade names, or branches for enrollment as a company/organization. If your legal status is a sole proprietorship/single person business, enroll as an individual. If you believe your business should be listed as a legal entity, have your business registration documents ready and email D&B. Complete business registration documents are required to verify your organization's legal status.