Hi mandywhite -
I'd like to confirm you are tapping the Arm/Disarm Status button at the top of the Overview screen.
There is a card that reads "See What's New" that will explain this & walk you through the process. I have also attached an image from the walkthrough which indicates the Arm/Disarm Status shield that you need to tap to bring up the keypad.
Are you able to access the keypad following these steps? If you are still unable to access the keypad, could you please send a screenshot indicating where you are experiencing the problem?