Easy to activate
To activate the add-on, simply visit the plugin page through the menu option: "Settings/Calculated Fields Form", tick the checkbox: "CFF-WebMerge", and press the "Update" button.
Enter the URL to the WebMerge document, and the correspondence between the variables used in the WebMerge document and the form fields.
Get the document's URL with the corresponding ID and key code, from the WebMerge service. The URL is unique by document.
Additional details reading a case of use in the following blog post: Generating PDF files at runtime with the information collected by the form