Pairing slim folio to iPad

You and ChrisJ4203 are clearly discussing completely different keyboards…

The Apple Smart (folio) Keyboard has no battery, on/off switch or bluetooth connection that needs to be paired with iPad - as it is directly connected to iPad using the three electrical contacts of the iPad Smart Connector:

Use your Smart Keyboard Folio or Smart Keyboard with your iPad - Apple Support

You clearly have a different keyboard - possibly manufactured by someone other than Apple. Perhaps you have a Logitech Keyboard?

https://www.logitech.com/en-gb/products/ipad-keyboards/slim-folio-ipad-keyboard-case.html

https://support.logi.com/hc/en-gb?webcontent=productfaqstub&mID=12852

For pairing Bluetooth accessories with iPad, see:

Set up and use Bluetooth accessories on iPad - Apple Support

You do not have to pair it. You just need to attach it to the iPad. What happens when you do that?