First of all, congratulations on finishing the game, (for real this time)! 🥳
I’m sorry that I wasn’t much help during the final stretch. I’ve spent the past couple weeks traveling, so I didn’t have any way to check the game for the solution to that ice puzzle.
The DLC should be available in the downloads section here - it includes a file with instructions on how to install it and then find the new content in-game!