I can't pair an old wireless Apple keyboard with the newest iPad

The keyboard was paired with a Mac Mini I have since given away. I hope I didn't need to disconnect the Bluetooth before doing giving it away. Still I wouldn't think it would be hard to connect the two. So Far I watched a couple of videos on how to pair it in Settings and that didn't work. We are running the latest stable iPadOS. I hope these devices are still compatible. I would love to know if anyone can tell what we are doing wrong.