ISLANDERS: Console Edition (UP)

This is pretty easy to unlock, you aren't required to place all of the buildings once you select the building pack you can keep them in your inventory, so when you've achieved the desired score needed to unlock a new building pack (indicated by a plus sign appearing in your inventory) you can select the plus and open the new pack. Keep saving buildings that aren't needed in your inventory and selecting the plus sign once this becomes available to add new buildings to your inventory, takes a couple of turns but is otherwise very easy.

As the game progresses and your building score goes up and up, it's easy to stack pluses in your inventory as well and then you can just open all of these at once to unlock the achievement this way also.

Focus on getting the highest possible score when placing the buildings. One thing to note, is the score is gained only one time when placing the building and not ongoing.