Mac user here. When the first book came out, I played through it and decided to only come back to it once the all the rest of the books came out. Now that book 5 is coming out, I figured I'd continue playing. Downloaded the latest release and fired it up, only to find the game doesn't see any of my saves. I looked around and found them in ~/Library/Application Support/unity.Red Thread Games.Dreamfall Chapters.
That folder has an Autosave folder and a StoryFlags.data file. I checked the modified dates and they're all from April 3rd and 4th 2015 when I was playing book one. When I launched the game, I didn't have a continue option, just a new game. I started a new game to see what would happen and it created an autosave file, but that file didn't overwrite the ones I already had. Actually I can't find it anywhere. I'm guessing if I find it and overwrite that location with the files from April 2015, all will be well. Any idea where it might be? I checked all the places in the FAQ, but the folder I listed is the only folder that had anything relating to dreamfall.
Edit: I found where the new saves go. They go in ~Library/Application Support/com.redthreadgames.dreamfallchaptersmac
So I took the saves from ~/Library/Application Support/unity.Red Thread Games.Dreamfall Chapters and copied them over to that folder. All is right in the world. Might wanna add that to FAQ.