you're welcome, too bad I can't help.
I tried running download asset for c-f character and it works fine. tried re-downloading demeter and diabolos by moving all my assets to another folder, works too. I added Neptune yesterday too.
I tried putting a desktop.ini on my nutaku folder, and it does give me that exact same error.
so yeah, I'm not sure how but that file should be there and it should be fine on Nutaku's end