Apparently you have to collect all 50 fragments to unlock it. They weren't very specific on the description in the kiosk lol.
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Well unfortunately it's not known to people that you get another quest at 50 fragments (I'm pretty sure.) just like how when you got to 45 another quest popped up. In pretty sure this is how this will work, but I can't be one hundred percent since its not possible to know for sure.