I have an iPad that it's locked and I need it to connect it to my MacBook Pro 2020 but it's a old iPad and my computer can't connect with the charger

Depending on your iPad model, you might need to buy an adapter or a specific cable for iPad-MBP connection.

After identifying your model with these instructions:--> Identify your iPad model - Apple Support, visit this page and see the compatibility:--> Power & Cables - All Accessories - Apple

Regards

Giulio

Presumably your Mac has a USB-C ports - while your iPad has a Lightning connector. If so, you simply require a Lightning to USB-C cable.

• USB-C to Lightning Cable (1m)

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