The addresses used in Part I nr 4 and 5 are identical.
Some people got the following question here:
The Individual indicates that this Form W-8BEN is being completed for Other Copyright Royalties. Information regarding the individual’s special treaty claim is required for treaty benefits to apply. Please provide information regarding the special treaty claim.
E.g the correct answers for Austria (IMO) are 12,0,Other Copyright Royalties, As a tax resident of the specified treaty country, I meet the required terms of the treaty. For other counties please look here: https://map.ais.ucla.edu/go/1004300
The pin above is sent to the mail you specified earlier in the process.