Charger

Most Apple iPads are now supplied with an Apple 20W USB-C Power Adapter:

• 20W USB-C Power Adapter

https://store.apple.com/uk/xc/product/MHJF3B/A

For iPad models with a Lightning connector, a USB-C to Lightning cable is supplied:

• USB-C to Lightning Cable (1m)

https://store.apple.com/uk/xc/product/MM0A3ZM/A

iPad models with a USB-C port are provided with a USB-C to USB-C cable:

• USB-C Charge Cable (1m)

https://store.apple.com/uk/xc/product/MM093ZM/A

If your unidentified iPad Air is a 3rd generation model, the cable you bought is okay for this charger:--> Buy 20W USB-C Power Adapter - Apple

If your unidentified iPad Air is a 4th generation model, you can use the same charger listed above, but you need a USB-C to USB-C cable like this:--> USB-C Charge Cable (1 m) - Apple

Regards

Giulio