for those who need to use ADE to read a book on the Kobo and are using Linux, I think I've found a way.
I installed ADE in Wine on my Linux box. Ubuntu even lets me double-click on an ACSM file and open ADE that will then import it in my library.
Problem is ADE on Wine does not recognize the Kobo so I was not able to drag the authorized books on the Kobo.
It turns out the solution is quite straightforward!
I simply went in the "My Digital Editions" folder (it should be in your home directory) and dragged the authorized files (ePub in my case) to the Kobo "Digital Editions" folder!
And I am able to read the book now.
One issue is that I have a book that in the "My Digital Editions" folder is split in 3 epubs and the Kobo shows them as 3 books.. oh well
UPDATE: actually it's the same book
I simply downloaded it three times by mistake