Gonna share my experience and hope it helps someone.
My updater was stuck at "updating set up files" but before i closed it, it looked like Jieun's picture too. i.e i started the dl before i went out and when i came back it was stuck at same place. Even tho it reached the playable stage each time i tried to open sc2 it will get stuck at updating set up files.
So i did a crt alt delete > task manager > and closed the blizzard agent updater. this forced it to refresh and when i opened sc2 again the patch starting downloading fine. i waited for the full download (1.32gb) before trying and it worked fine too.
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