By default, the standard donation form you can create in the merchant dashboard only contains the donor's email address and donation amount fields. If you would like to add additional fields to the form, you must do so through the dashboard and regenerate the HTML form code.
The additional required fields you can add to the donation form are:
City of employment
As well as parameters that modify how the form functions, like:
Max donation enforcement
Max donation amount
TIP: Our testing environment(https://test.bitpay.com/) is a great way to experiment with options & changes without affecting your live donation form.