steam in all its wisdom has decided that mods should not be downloaded from steam into the game's pre-provided MODS folder but rather in a "Content" folder at C:\Program Files (x86)\Steam\SteamApps\workshop\content\289070
"289070" is Steam's designation for Civ6. All your downloaded mods will be folders within this "289070" folder. They are sent to folders with numerical folder-names that match to the Steam Item's ID #.
Not confusing in the least.
(btw the specified folder-path is for Windows machines. Macs are located somewhere in something called "Libraries" as I recall from what people have told me.)
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This Steam goofiness has no effect on mods you manually download and unzip from here or elsewhere like reddit. You still just place those in the reasonable place: the game's pre-provided MODS folder. Civ6 will find the mod in either location, but it will certainly be far easier on you to find manually-downloaded mods where you expect to find them, and shown with folder-names that are far simpler to grok.