This is an unfortunate circumstance where the button to proceed is hidden due to the way iOS treats the application in scaling mode.
If you can please follow the steps below to turn off the scaling mode you should be able to proceed.
Steps to turn off scaling mode
Go to Settings
Scroll down and proceed to Accessibility
Under Accessibility click on Display & Text Size
In Larger Text if its set, please toggle it to Off
Go back to the SteadyPay application to see if you can now see the button to proceed.
If you still run into this issue please let us know.