PA & NJ are reciprocal states - they don't tax the wages of each others' residents. So, your NJ employer is properly withholding PA taxes - NJ cannot tax those wages because you are a PA resident. Unless you have income from NJ sources other than wages, you do not have to prepare/file a NJ return.
If that's the case, in Personal Info be sure to indicate that you did not earn money in any other state. If you select Yes there and select New Jersey then you're telling TT that you need to prepare and file a NJ nonresident return - which you don't.