I am going to stay at Beijing Marriott Hotel Northeast.

You can take the line 10 at T3 but why do you take the line 10? If you want to get to the hotel, the line 1 is the most suitable and you just need to get off at Sanyuanqiao station and walk about 20 minutes to the hotel. The running time of the line 1 is from 07:00 to 01:00 on next day and the bus leaves within 30 minutes.

Hotel website says line 10 is only 0.4 miles far.
(Line 10 Airport Express) SanYuanQiao 0.4 miles NW from Hotel

I found the line 10 on the airport official website that doesn't stop at SanYuanQiao but the line 1 does. So you can follow the route I told you or you can call the hotel for more information.