By the way, looking at your screenshot, I hope you are aware of the “calculation order” issue. In your form, it is important that some fields are calculated first, and other fields later, and the final field last of all. Being aware of this in advance will save hassle later on.
With FormMaker, a number at the end of the name of a form field (which is set in InDesign’s Buttons and Forms panel) decides the calculation order for the field. The higher the number, the later the field is calculated.
For instance, if one field is called “Text Field 3” and another is called “Text Field 10”, and both have calculation scripts attached to them, the calculation script attached to Text Field 3 will be run before that of Text Field 10.
More details here: https://www.id-extras.com/help/formmaker-help/