I played a while ago and everything was broken, and had to jump through some hoops Bioware hasn't bothered to tell anyone about.
1. In game DLC downloading is broken.
2. Need to download the files from Biowares social network.
3. At the social network they don't give you everyhtong you need. So using "The stone prisoner as an example:
Download the file from the social network they provide , but then to activate it, some files also need an "Offer File" found here: http://dragonage.wikia.com/wiki/Downloadable_content_(Origins
) I know Stone Prisoner was one example (and I even had it from CE, but it didn't work without this offer file).
4. Install the Offer file and the main file with the mod installer. The mod will then appear on the map - Stone Prisoner caravan for example, I forget if the journal entries were missing/appeared.
I had to repeat this for several mods - Wardens Keep, etc, but got it all working. Obviously ensure you're logged into their network.
...All of that messing around compared to CDProjekt's installer for the Witcher 2.