Book the SHA Plus+ hotel and then the two tests via PSAS.
Make sure the image you upload has both the hotel and PCR test receipts. I screenshoted each receipt and used MS Paint on my computer to put them in the same image.
I didn't get transport via my hotel, I just got a taxi from the taxi counter at the testing exit. I was under the test and go program, so I am not sure if sandbox requires pre-booked transport. If you want to be on the safe side, organise it through your hotel.