Thank you for the kind words!
We definitely could have done a better job at communicating the map completion mechanic, I'm seeing many comments about people not getting to the score screen.
The way it works is that when you drag all of the pieces somewhere over the outline of the island you get a prompt to mark the treasure. Even if you get all the pieces wrong you should still be able to dig for treasure. The accuracy of your map defines whether you get to dig up the famous treasure of Salty Paws or something else.