Prior to continuing, it would be prudent to make sure the issue you are encountering is not occurring as a result of an application conflict. The best way to proceed would be to try loading under a new Window's Administrator account and in a "clean boot" state.
Create a new Windows Administrator (<--important that its an Administrator) account:
Windows 10\11:
http://windows.microsoft.com/en-us/windows-10/create-a-local-user-account-in-windows-10
Log in under that account and try. If it fails, and while still under that account, please click the link below for performing a 'clean boot' under it:
https://support.microsoft.com/en-us/kb/929135
After you've loaded Windows in a clean state, please try once again.
Purging game installation
Please uninstall GC4 from Epic Library:
After GC4 has been uninstalled, please press the Windows key and "R" at the same time. In the window that appears, paste the path below and hit enter:
%userprofile%\Documents\My Games
In the "My Games" folder, rename any folders related to 'Galciv4' to 'Galciv4_OLD'. Upon reinstall (if that is the goal), a new folder will be created.
Once again, press the Windows key and "R" at the same time, and use the path below:
%programdata%\Stardock
You should see a folder named "Galactic Civilizations IV", please rename this likewise as well.
Lastly, please navigate to the location where you installed the game - typically that is:
C:\Program Files\Epic Games
If a GCIV folder exists, delete it.
Restart your computer and reinstall GC4 using Epic Client. After it has completed the installation, please create a new game to see if your issues persist.