They are all filled in and different, I even changed the integration name but the channel icon isn't changing to the WooCommerce one (as per Royal Mail's guide).
As a last resort, I checked if WordPress had a click and drop plugin that would handle the integration with Royal Mail. It seems the click & drop site is the only way.
Maybe it's time to give a technical person in Royal Mail a call, or maybe there's e-mail support. I'll be damned if I can find the right details!