trying to download digital editions 3.0

Hi. 

I recently downloaded ADE 4.5.2 but it isn't working properly with my old Nook.  I had the old version of ADE before and it worked fine with my Nook and I'm getting fed up with the errors not allowing me to read ebooks I check out from the library on my nook.  I want to try downloading ADE 3.0 since that seemed to work fine but I can't find a link to download it.  The link for 3.0 on the digital editions website just goes to a list of all the Adobe products and doesn't seem to include ADE 3.0 anyway.  Please help!   Where can I get 3.0 back?