This certainly sounds and looks very strange, but the person behind this seems to be a legitimate person who is indeed a researcher.
https://www.hkubs.hku.hk/tc/people/sichen-dong/
This may actually be a real survey, but being conducted in a non-appropriate way
I have not yet seen the "you have to be logged in to get your reward" message so I am not sure where it is and of course I discourage everyone from logging in it