Provisional Driving License (PDL) approval is done by your driving school not NTSA. To check whether your PDL has been approved, login to your NTSA TIMS portal, click on test booking, if your PDL has been approved, you will be able to book a driving test.
If you are getting an error message like no pending application, then your PDL has not been approved by your school.
Your PDL has to be approved twice. The first time is when you joined the school and the second time is after atleast 21 days from the day you joined the school. The 2nd approval is to enable you book your driving test.