The vehicle registration differs from the vehicle inspection sticker. The vehicle registration is just that. A registration of your vehicle with PennDot. The inspection sticker is proof that your vehicle is following the state equipment safety regulations (i.e. it's operable).

The PennDot Notification on the website is referring to how PennDot used to mail your vehicle registration to you and you used to get a sticker that you would put on your license plate to show that the vehicle was registered. But they don't do that anymore and all you need is to have a copy of your vehicle registration.

The inspection sticker is different though. You need to schedule a vehicle safety and emissions inspection with a mechanic. The cost can vary. Some places will do it for $30. Larger mechanic franchises and the dealer may change upwards to $80. The real issue is that if your car has safety or emissions infractions then you'll have to pay for the repairs until you can receive your inspection sticker. Those can be costly depending on what they are. For example, I just had my inspection and needed to get new brake pads. The dealer tried to charge me $500 for them, but a smaller shop did it for $200.