Errata:
Why do You need to receive a mail to discover how to create an ADE id, to authorize You PC and to authorize Your Kobo?
Correction: Adobe effectively sent to me an email: "
Dear Customer, you recently created an Adobe ID. The Adobe ID is .... (my email). To confirm your email address, click on this link: ..."
Did You check if the mail is finished in the spam? It is the first thing I can think. Or may be also that the email You wrote was not correct.
At worst get a new email address and create another ADE id with it and see what happens.
To create a ADE id and authorize Your PC:
https://www.youtube.com/watch?v=Jb-JgRH_FEc
And to authorize Your Kobo:
http://prod-www.kobobooks.com/ade