Hello @Ann289,
I would inform your guest that she must be present at check in. I would not let anyone in unless the person who made the booking was present. Make sure that this message is sent in an Airbnb message. I would call or message Airbnb to advise them of my intention. Phone and message links can be found by clicking on "Help", then on "Visit the help centre" and then on the "Contact us" button near the end of the page.
One other point is that I see you say that check in time is anytime after 2pm. It's usually much better to have an end time set as well, as in 2pm to 8pm. This is because the guest can now arrive at any time they state and Airbnb will not support you if the guest drags it out until,say, midnight. With an end time specified you have freedom to be away in the evenings and Airbnb is likely to support you if a guest turns up after checkin time ends and complains to them that they can't get access to your place.
With an end time set, you can, of course, always come to an individual arrangement with a guest for late check in if it's requested in advance and it suits you that day.
Steve.