IMPORTANT! Make sure you sign up with a fresh account and sign up as a company.
Create your Apple ID here https://appleid.apple.com/account, once created make sure you write down the security details as you will require these later on in the process. This must be a real person.
You must Enable "Two Factor Authentication", this has to be done on an Apple device. Pleae note this is NOT "Two Factor Verification". More information https://support.apple.com/en-gb/HT204915.
Find your DUNS ID Number https://www.dnb.co.uk/duns-number/lookup.html search for your company and the ID Number will be emailed to you, all Limited companies will automatically have one, if you do not have one you will have to create one follow details on the site. Note this down as you will need it in the next step.
Go to https://developer.apple.com/enroll/ and sign in with the account just created above, click in "Join Developer Program"
Pick the option Enrolling as an Company/Organisation. Apps published to a Company/Organisation Developer Account will display the Company Name entered within the iOS Developer Account.
Select your choice and click Continue.
Please note that your company is recognized as a legal entity in your country.
Fill in your contact information and make sure that your legal name and country are correct. Read the Apple Developer Program License Agreement and click on Continue.
Confirm the Apple ID Information, Entity Type, and Contact Information and click on Continue.
You are given an option to get automatic renewals. If you wish, select the auto-renewal box. Click on Purchase to enroll and pay for yearly iOS Developer Account.
Sign in using your Apple ID and password.
In order to setup your yearly iOS Developer Account, fill in the billing information and click Continue to complete the payment.
Fill in any remaining information on the next screens. Apple will send you a confirmation email within 24 hours. After receiving the confirmation email.
Login to https://appstoreconnect.apple.com/ with the Apple ID created at the start, read the Apple Developer Agreement. Check the By Checking this box I confirm that I have read and agree... box and click on Submit.
Go to App Store Connect https://appstoreconnect.apple.com and log in again with your developer account. Then click on Users and Access.
Click on the blue + icon behind Users.
At First Name, you can fill in Data and at Last Name you can fill in Master. Fill in firstname.lastname@example.org again. Tick the Admin box under the header Roles.
Then click on Invite.