If your school is using SchoolOnApp then you have to get 'school code' from your school.
To login as parent you need to enter your mobile number as user id, then you will get OTP. After verifying the OTP you will be logged in.
To login as student you need to enter your Admission number/SR number as user id and your default password as 'firstname + lastname'.
If you have any problem then contact at your school.