Kobo on a different ADE

This is weird, I have a MAC. I can download and read my Kobo books (purchased under my Kobo account) but cannot synch with a Kobo Pocket reader. When I linked my pocket reader it grabbed my work ADE (different sign-on from my Kobo account) so it now "masks" books on my Kobo account. SO, why is it that I can access my Kobo ADE through the computer app but CANNOT download them to my pocket reader? When will ADE enter the 21st century and allow management of two accounts on a computer?