The check-in process is very easy - Vivian will message you the codes, and you'll let yourself into the apartment. The apartment itself is very cosy and clean, even better than the pictures, and many of the amenities you could need are provided for (toiletries, towels, water, tea, cooking utensils, etc.). The apartment is also in a very good location, probably less than a ten-minute walk from Mongkok MTR on Kowloon Island. The neighborhood is very lively and bright, with plenty of shops and restaurants around, but the actual street you live on is nice and quiet (although not sketchy, don't worry).

Vivian is also a wonderful host. She provided a PDF of important info (how to get to the apartment, house rules, etc.) and responded very quickly to any inquiries or problems that arose (a.k.a. I accidentally locked myself out of the apartment because I forgot she explicitly wrote in the PDF to not touch the inner door's lock, and she went to a lot of time and trouble to let me in again, which was very kind of her).

All in all, I would definitely recommend staying in this apartment if you are a single traveler in Hong Kong!