Today Skyrim Special Edition received a new update, from 1.6.640 to 1.6.1130.
With it the “Mods” and “Creations” menu were consolidated into a new UI and paid mods are back, the new UI also lets you organize your load order and browse free mods which was already possible before.
The update also added a new resource pack (I assume these are “free for modders to use”) and broke SKSE-related mods, the paid mods seems to be only from “recognised” mod authors like TrainWiz who worked previously in the CC, and you might know him from the Thomas the Tank mod back in 2011.
Note that this only affects the Steam version of the game, the GOG version has no in-game modding menu or creation club because it was stripped from all online functionality.
Here’s a list of the creations that you can buy in this marketplace.