In some cases, your fillable PDF document will contain fields that you want to always fill with a default value. In order to do so, open the PDF mapper, navigate to the PDF page that contains the field you wish to map and click on it.
In the Field Details panel, type in the default value you wish to use or insert a “macro” from the dropdown.
Note: The "default value" in the PDF mapper will only be used if there's no "connection". For example, if the PDF field is connected to a template field and that template field is left blank in the engagement, then the "blank" is what will be used to fill in the PDF. The default value in the PDF mapper exists for situations when we do want a value to be filled in the PDF but we do not want the client to have to go through inputting it in the engagement.