how can we go to Crown Plaza Kowloon East from HK Disney by train?

Well, there is no direct subway that can take you to the hotel. It needs to transfer four times.
So you are suggested to take bus no.R8 to get to Lantau Link Toll Plaza/Lantau Link Toll Plaza first.
Then transfer to bus no. E22A to get to Tseung Kwan O Station, Po Yap Road. After that, walk north around 270 yards to find the hotel. It takes around 95 mins. And the ticket fare is 27 HKD per person.