Use Aldiko...I also have the same device and can download all my books, including DRM'd and library books to it. Get version 2.1 which is for tablets.
- Go to settings, key your ADE username and password first
- go to store
- using the menu icon in the upper right corner, select catalogs
- tap +
- enter library name (Calibre)
- enter url :
http://192.168.1.xxx:8080
The xxx is for your own LAN number in use (LOCAL AREA NETWORK) that you can find doing a command prompt on your computer and using the command "ipconfig"
If entered correctly, you will see a menu which allows you to select which books to load directly from Calibre
Make sure that Calibre server is "on" and that the port it is using (in calibre preferences, sharing over the internet) is 8080.