Albert's macro either
a. gets the field names and values that are actually displayed on the form
and export them to a delimited text file. That's if you click the "merge one
record" button, or
b. executes a SQL query that you supply and exports the results to a text
file, if you click "All".

As I understand it, an Access subform will typically be populated  with data
that is related to the main form using query syntax that references the
form. e.g. in Albert's sample, there's a query with the text

SELECT Contacts.*
FROM Contacts
WHERE (((Contacts.City)=[forms]![contacts]![city]));

which clearly references a specific form and field on that form.

I think you should be looking to get you data using a similar query, but you
really need to run this type of query within Access while the Form is open,
not from outside Access.