Where is the Get Amount From option in the Authorize.net integration?

would like to pass results from a Calc field to my Authorize.net payment wizard.  I've seen it on PayPal widget but not seeing it on Authorize.net wizard.  Where is it?

Get Amount will only appear in the payment configuration if you have a textbox field with numeric validation or a calculation field.

https://www.jotform.com/help/275-How-to-pass-a-calculation-to-a-payment-field