hello! have you followed the installation instructions?
1. Unzip neo-cosmos-win.zip. You'll find a folder called aa.
2. Go to the folder where A Dance of Fire and Ice is installed.
3. Paste the aa folder into this path A Dance of Fire and Ice_Data/StreamingAssets.
After you run the game, the Neo Cosmos DLC should be available.
Hope this helps! In case you keep running into problems, you can send me an email to giacomo@7thbe.at