Install the dazip using daupdater. This updater is located where you installed the actual game in the bin_ship subfolder.
The path is normally: "C:ProgramsDragon Agebin_shipdaupdater.exe"
If you installed to another drive or location you can find it there in the "Dragon Agebin_ship" folder.

Make sure your game is not running and go to that directory and run the daupdater.exe,Now you can just drag and drop the .dazip file into the window that opens OR select it from your download location by pressing the "select DAZIP"-Button.

When you have done that you see the .dazip file in the list, (you could add more than one file and install them all one after the other) now select it by clicking on it and press the "install selected" button.Don't get irritated by the loading bar that isn't fully filled, when it says installed then its done.You can check the successful installation when you click on the log tab, at the end of the log it says that it succeeded. (or that the Installation was canceled because there was an Error, normally with a fault message/mention of the file that caused it).

Once you load a savegame, the robe will spawn in your inventory.