Go to Configuration - Partner (Add on) Settings - Shipping Services Config
Click the blue add services button in the top right
Click on Royal Mail Icon
Populate the form, all the fields with a star * next to them are required.
Now you've added Royal Mail to your account you’ll see it appear. If it’s all filled in correctly Royal mail will soon be in touch with your account details.
Please note, It can take up to 5 days for your Royal Mail account to be created.