@Hrvoje5 The guest has just filled the place where they can request a different check-in time and thinks that entitles them to check-in then.
As I said, I'd just send them a message letting them know that while they can request a check-in time outside the one stated in the listing, they shouldn't assume that it can be accommodated, and in fact you can't accommodate it. That they need to give you a check-in time within the time frame stated on the listing, i.e. after 2PM.
And maybe contact Airbnb to say the reservation states a check-in time not in line with your settings and ask why this was allowed. If they try to quote you useless info about how to set your check-in window, tell them your setting is correct and that is not the issue.