As you are doing an offline activation I think you'll need to contact Tableau Support to get an updated Product key....
Can you please post back to let us know how you get on?
Ciara, thank you very much for your reply.
I did succeed activation.
The problem was my mis-understanding of the sentence, "open a command prompt as an administrator".
It is necessary to open the command window as the figure. Sorry for Japanese in the figure.
The difference between admin & nonadmin windows is also identified by the text of the bar.
Hi Junwa, glad it's sorted now, thanks for letting us know