@Jessica2690
Beautiful listing by the way. I used to live in Cape Town many moons ago (I miss it) so I know your location is also excellent. I am sure you will do very well.
You have already gotten some sound advice here. I would try texting the guest if the WhatsApp message is not being delivered. Guests often don't have WiFi when travelling. If that fails, call them and, if that fails, contact Airbnb and ask them to try to get hold of the guest.
The main problem here is that you haven't specified when your check in window ends, just that it starts from 2pm. That is going to make guests think they can come at any time from 2pm to midnight or even in the early hours of the morning, which I assume is not what you want! You should definitely specify what time check in ends.
Did you have any communication with the guest prior to this about their ETA? I always ask guests to tell me their time of arrival in advance. Most guests will give me a specific time and then I just ask them to please contact me if they are running late (and provide my number again in case they have missed it on the booking). If they give me a window, e.g. between 4 and 5pm, I usually ask them to let me know when they 10 or 15 minutes away. If they give me a window of more than an hour, then I will ask them to be more specific closer to the time or on the day.
Of course, some guests will not show up at the agreed time and not bother to let you know, but those are now quite rare. Having had this conversation in advance, I find that guests treat the arrival time exactly as @Anonymous puts it, as an 'appointment'.
You don't want to be sitting around waiting for a non-responsive guest for five hours or more. Even if you are going to be home anyway, it's incredibly frustrating because you can't really get on with other things if you think someone might arrive at any minute.