Hi,
You have to use renderPDF service if you wish that dynamic interactive pdf form will be the output of your process.
Set the name of your xdp template in the "Form to Render" field, name of the xml file data as a "Form Data" and enter the path to your template as "Content Root URI".
In the output section set the name of the variable to hold the rendered document in the "Rendered Form" field.
Note that the path should be started with: "repository:///" and then the path to your template.
For example if the name of you tempate is form.xdp and it is located in Forms folder of your repository, you should set form.xdp as Form to Render and "repository:///Forms" as Content Root URI.
Hope this helps,
Yan.