I see in the car rental order that there is a "highway fee box". How do I use it? Is it the same as our ETC? Do I need to go through a dedicated channel? Will it be settled together when I return the car? Have you used it before ?

That's E-toll, a small electronic thing stuck on the car, which will beep and automatically deduct money when entering a toll expressway. However, you can use navigation to avoid toll expressways. I have lived in Australia for several years and basically don't drive on toll expressways. However, I'm afraid that I may accidentally enter a toll expressway sometimes. It's fine the first time I accidentally enter, but I will be fined if I accidentally enter again.