Yup I have the same notification in my library when I went to install it.

IIRC it had it from the beginning. D/L the installer from the regular account library should work.

Click on Hearts of Iron 3 in your library and it will take you to the Galaxy page where it says not yet available.
Click on the More button.
You will see on the left side make a back up copy which will show both the game and the DLC select both and the installation files will download to your PC..
On my Win 7 64 bit they can be found in C GOG games open the file and the first file is headed downloads.
open it and you will see the HOI 3 files.
I usually then drag the files to the desktop to run them.

If you're not familiar with the old GOG system open the HOL 3 folder (unzip them if necessary) and click on the gold square with a white circle and the game will load onto your hard drive then do the same with the DLC's.
once installed you have no need to keep the the installers unless you wish to use them to reinstall at some time and don't wish to download everything again.

Yes it's working now. Thanks!

Having an issue on the start up screen for HOI3 the one where it has the top botton check for updates and the bottom button start HOI3 problem is the box bottom area looks all duplicated which puts the start button off the bottom of the screen where I cant click it. I tried to resize the box but it does not allow. The start button is right under the edge of the box and I have had to use Win 7 compatibility mode to be able to see the box. I'm running EVGA 1070 4k Gsync laptop 64bit Win 10. Thanks