Additional Field Workaround
Currently the only fields supported in the autoresponder form are the NAME and EMAIL fields.
However there is a workaround for adding additional fields of your choice such as Phone, Zip code, Address etc.
You can direct your customers to the hosted form on your Autoresponder, if it has this feature, by hyperlinking your Button Text in Step 1 directly to the form and bypassing Autoresponder Integration in PageDyno.
PageDyno
How to get the URL to place for the Button Text Hyperlink
Aweber
MailChimp
GetResponse:
Many other autoresponders have this feature - just check the help docs for your autoresponder or contact their support.