Is there a way to purchase a ticket at the Newark station or do I have to purchase a pass online?

There is station at Newark that is currently under construction, it's not open yet and I'm not sure when it will be completed.

When is the Newark Delaware train station open so I can go inside?

I have bought a ticket at Newark

There is no ticket office at this station.

You can pay cash on the train if need be. May cost a bit more.