Two things:
1. As I mentioned before: "If the source data changes, the table (a pivot table) will need refreshing (right-click it and choose Refresh).". This is not automatic (but it can be made to be).
2. If you're using Excel 2016 for Windows my attachment to post #3 should work.
Adding rows to the source data should be as easy as writing new entries immediately below the existing table, or pasting data to the same place. Just make sure the table extents cover your data (a small symbol in the bottom right corner of the bottom right cell of the table is apparent and you can click and drag it to cover your data, but this shouldn't be necessary since the table should adjust its size automatically.


I know nothing about the Mac versions of Excel but I suspect they don't have the Data Model. So I'll wait until you try it at work. Try the file I attached directly at work, don't use one you've first opened and saved on your Mac.