On Mac:
1. Download the DLCs and extract the contents, on Mac it does it automatically, so you should end up with two folders: one called step 1 and another called step 2. Open step 1 (or 2) and copy the contents.
2. Right click the Our Life application and select the "Show package contents" option, the computer will then open a new window with a folder called "contents" . Open it and you will then see 2 folders and a .plist file.
3. Open the Resources folder, and within that open the autorun folder
4. Inside the autorun folder you will see a game folder, open it and paste what you copied in step 1 into the game folder
I don't have a windows but I assume it would be a similar process of copying the items from the DLC folders and looking for the game folder
Thanks for answering to help,