In order to setup your Apple Developer Account as an organization, you will require a D-U-N-S Number
You can view all details related to a D-U-N-S number here or read below:
What is a D-U-N-S Number?
D-U-N-S Number is a unique nine-digit number (standard business identifier) that identifies business entities on - location-specific basis. This number is authorised, assigned and maintained by Dun & Bradstreet (D&B). On part of the enrollment and verification process for your Apple Developer account as an organization, your unique D-U-N-S Number will be used to ascertain and check the identity and legal entity status of your organization.
D-U-N-S Number is required if you're enrolling as a company, organization etc. If you're registering as an individual on the Apple Developer Account, you may not require a D-U-N-S number
How to create / get a D-U-N-S number?
To view your organisation's D-U-N-S number, you can use the D-U-N-S Number look up tool
If you're registering first name for a D-U-N-S number, you will be asked for the following business information:
Legal name of your company / entity
Registered / headquarter address
Mailing address
Contact Information
You may also receive a verification call from the D&B team.