Same.

I would like to know the answer to this question too please.

Ditto. I also picked it up for Japanese (quite a while back) and saw Korean is one of the new free to play languages, but I apparently can't use it without buying it (even though the update said it was going to be free).

Same here, launched the game and only have the languages I have previously purchased, but not Korean

Hi guys, I have written a guide for people like me who previously owned the game. I just went through the process and had this prepared so you can avail of the promotion too!
https://gtm.you1.cn/sharedfiles/filedetails/?id=2066348192

That is a ridiculous hoop to have to jump through for someone who previously paid for the damn game.

I didn't have (much) trouble with this, having purchased the Spanish pack previously. Clicking the button to play the free version just launched Influent as usual with Spanish only. But in the list of DLC, the French Italian and Korean packs are listed as free. I clicked on the page for French, clicked download, and all three missing language packs were downloaded and installed. No problem.