The built-in forms of Amplify/Engage/Capture support by default name and email fields only.
However, if you want to integrate your custom opt-in forms with phone number for example, or any other custom field, there are actually two ways of integrating custom opt-in forms :
- If you want to preserve the design/style of your opt-in form, use the widget located at « Misc » -> « HTML Code », drag & drop it, and go to its settings ,then copy your form’s HTML Code and paste it in the setting « HTML Code.
- If you want to use built-in design, use the widget located at "Forms" -> "Custom Opt-in Form", to set up your custom form to use your custom HTML code, check the following link : How to integrate my autoresponder? [HTML Code option]
You're free to try both widgets and decide which one works best for you.