I have the same problem.
I bought sins of a solar empire game of the year edition . It is the version 1.165, the game was offered with a french magazine "PCjeux"
the game is registered on stardock, in my account it says that it is for a digital copy of the game and that i need to install gamestop app to download the game.
I did everything it said:
create an account on stardock, register the game, create an account on gamestop with the same id and password, downloaded gamestop app but i installed the game with my cd cause i didn't find a way to download with gamestop.
on gamestop it says that there is an update available but i can't update because gamestop says: "you have not yet entered a product code for this product. registering the product is required to download updates. please register this product with the gamestop app and try again."
I would like but there is no way to register with it.
I also have stardock central but it's always empty.
So, what? did i just lost my money and my time with this game?
I have already send a mail to email@example.com, so wait and see.
Edit: the support said that the game doesn't and will never work with gamestop. they gave me link to download a standalone version of the game with the latest update. So, problem solved.