If you're using listFolder to list the contents of a shared link that refers to a folder, you'll need to use recursive:NO, since the recursive mode isn't supported when listing the contents of a shared link that refers to a folder.
If you need to list the contents of a subfolder inside the folder for the shared link, you need to then call listFolder again, specifying the same shared link in the sharedLink parameter, but also specifying the relative path of the desired subfolder as the path parameter (the first parameter).
You can build the relative path based on the "name" property of the relevant subfolder in the results from the first call. For example, if the results of the first call shows you that there's a subfolder named "Receipts", then you would pass in a path value of "/Receipts" to list that subfolder when you call listFolder again.
I understand that I can just call the files_list_folder() and pass '/entries_loop_variable.name' as path while looping through the files_list_folder_object.entries, to include the subfolders and files inside the list of files. Is that right?