Permission issues are the number one cause of S2-sp64-ship.exe errors.
How to Fix "S2_sp64_ship.exe" Crashes in Call of Duty: WWII on Windows 10
If the .exe file itself was corrupted during download, Steam can fix it.
: Denotes the Single Player campaign executable (multiplayer uses s2_mp64_ship.exe ). 64 : Indicates it is a 64-bit application.