I believe it should be made clear from the description that there is a second room which is being rented out - as I discussed with Njabulo. The reason is simply to allow guests to make an informed decision as they may not feel comfortable sharing a flat with people they know nothing about (for the host you can read reviews), especially with Covid.
In the end, I decided to stay for both nights I had booked despite being given the option to cancel. But I would have preferred to know all the relevant information before booking (should you have any questions about the safety measures put in place for Covid, I would suggest to message Njabulo).
Njabulo is polite and responsive. He managed to arrange my check-in while he was at work despite my last minute booking. The room was comfortable and clean.