The process described only works in the US. Internationally, you need to contact DNB and go through the multi-week horror. Eduardo appears to be in Brazil.
Having said that, the submission process didn't explain what a DUNs number was important for and it seemed like a weird thing to need...i share the frustration.
I was stuck last year with a tight deadline for one of my enterprise apps (which needed the DUNS for me to publish) and I used this method; it cost me nothing and was complete within a few days.
As far as I'm concerned it's just another business number that I need to apply for.
You won't get far in business if you don't have the patience to put up with all the stupid paperwork.
[1]https://developer.apple.com/ios/enroll/dunsLookupForm.action