Yes, the children still need the visa to travel to any country if they are holding a separate passport. Minors under 18 can not apply for e visa if they do not have their guardian. Parents should, on behalf of them, apply for an eVisa with their personal information such as their names, date of birth and passport details.
If you have more than one child, make sure that they all have their own valid passport and do not use the same passport for them. The process will be the same, and the result will be sent in 3 working days. However, if you want to receive the result faster, please choose the Rush Visa option.