You must stay in Cambodia for 10 days, but you don’t have to remain in one place. To prove your stay, you need to book a hotel for a few days. They will also check the entry stamp in your passport.
I had a similar situation, I guess, but I'm not sure if it was my fault or theirs. Anyway, I was applying for a DTV visa from Cambodia, and I received it with the wrong country in the passport section.
Yesterday, I came to Thailand for the first time on a DTV visa. They didn’t even look at my printout, he had all the details on their computer. What’s the point of printing it?