1) If the value is coming from an upstream node then you can delete the current SourceFile = ... line in the ConfigureFields script and put a corresponding statement in the ProcessRecords script.
SourceFile = in1.MyZipFileField
You will also need to move the code that extracts the files from ConfigureFields (lines 17 - 20) and put it into the ProcessRecords script (after the last line)
2) If the value is being typed in then you would need to a Data Flow Property Reference or a Run Property Reference and replace the contents of the string in the SourceFile = r".." statement with the Data Flow Property Reference or a Run Property Reference. The existing statement in the code would then be something ike:
SourceFile = r"{{^MyNewPropertyRef^}}"
See the Defining properties topic and Using property references topic in the Help documentation.
You may want to set the property type as 'Filename' as this would present a file picker in the UI

