Add bottom to Chrome extension

I have an open source Chrome extension (seems to be written in Java or Json) that runs through a loop of a process in a webpage.

In this loop, the app enters values in a given webpage, and then save the values calculated by the webpage.

The webpage also have a button to download more detailed calculations, but the app does not include the functionality to download such a file.

I am looking for an expert in Java (or Jason) to implement this modification to the existing app. Basically, I need to add a bottom to this app to download a file of the calculated values at each iteration of the loop.