You can only submit your run after your race starts, but before the race ends. So, for example if you have a 30-day race and today is the 29th day, you can still submit your run the next day. But if you run on the last day, you can only submit your race before 00:00 (GMT+7).
If it's a one-day race then you have to submit your run on the same day before 00:00 (GMT+7).