OTC GOG vs Steam

Hi there I have Offworld Trading Company both on Steam and GOG . There is file differences between two version but I can understand that . Because , GOG version don''t have Lobby Matches .

Galaxy.dll ERROR: Checksum did not match.
Offworld_Data\globalgamemanagers ERROR: Checksum did not match.
Offworld_Data\level0 ERROR: Checksum did not match.
Offworld_Data\level2 ERROR: Checksum did not match.
Offworld_Data\level4 ERROR: Checksum did not match.
Offworld_Data\level6 ERROR: Checksum did not match.
Offworld_Data\resources.assets ERROR: Checksum did not match.
Offworld_Data\sharedassets2.assets ERROR: Checksum did not match.
Offworld_Data\sharedassets2.assets.resS ERROR: Checksum did not match.
Offworld_Data\sharedassets4.assets ERROR: Checksum did not match.
Offworld_Data\sharedassets6.assets ERROR: Checksum did not match.
Offworld_Data\Managed\Assembly-CSharp-firstpass.dll ERROR: Checksum did not match.
Offworld_Data\Managed\Assembly-CSharp.dll ERROR: Checksum did not match.

Those are probably for that . But one file seems not there in GOG version

gamedata.dat ERROR: D:\Steam\steamapps\common\Offworld Trading Company\gamedata.dat does not exists.

Is that file missing from GOG version or only used by Steam version or something different ?