I've just obtained them through the Kobo Desktop (v1.9) and then synced them to a Kobo WiFi via USB.
I am seeing the covers for all three books in both locations (desktop and Kobo WiFi).
Now you could also download those books via ADE; go to the Kobo website and then "My Library". In the "I'm Reading" section you will see all the books you have, and the Delver books will have the option next to them "Adobe DRM EPUB". Clicking on the buttons for those three books will download three "ACSM" files that when opened will use "Adobe Digital Edition" (ADE) on your PC to download the three ePubs to your PC.
These you can just sync via ADE to your Kobo Touch, or add them to Calibre and sync them from there. Since they still DO contain DRM you will not be able to use all the Calibre features to manage them.