Error code - EXP2 Crusade partial install

Sorry to hear you are having trouble.

First opt-in to the v4.1 hotfix beta.

To opt-in:

1. Select Galactic Civilizations III in your Steam Library
2. Click the gear icon in the upper-right, or right-click the game in your list, and select Properties
3. Click the BETAS header on the left-side of the dialog
4. From the dropdown, select opt_in_update - Steam will automatically update your files

Then go to the folder

\Galactic Civilizations III\DLC\

and delete the folder

EXP2_Crusade

Then run the game, you should only have to do this the first time before you run it.

Thank you for your patience and patronage.

A thousand blessings, Rhonin!  It worked!