@Gori the Grey if you take a look at the Steam DLC page, you will see that the DLC are not limited to Civs -- there are also map packs:
https://store.steampowered.com/dlc/8930/
Those have caused problems in the past (for example in the original Deity Challenge Lineup) when someone who had the map packs posted a saved game, and those who did not have the map packs could not play it. There was a method of removing the reference to the map packs from the saved game, which involved using a plain text or code editor to replace the header of the saved file. I used it myself a few times, but I have forgotten how it was done. Trawling the forum might reveal posts about the method.
https://store.steampowered.com/dlc/8930/
Those have caused problems in the past (for example in the original Deity Challenge Lineup) when someone who had the map packs posted a saved game, and those who did not have the map packs could not play it. There was a method of removing the reference to the map packs from the saved game, which involved using a plain text or code editor to replace the header of the saved file. I used it myself a few times, but I have forgotten how it was done. Trawling the forum might reveal posts about the method.