Sorry for so many issues, but if you don't know about them, you don't know.

in Sample_05_Chart_with_PHPExcel.php
line 69,70:
$shape->getPlotArea()->getAxisX()->setTitle('Month');
$shape->getPlotArea()->getAxisY()->setTitle('Downloads');

do not appear to be working:

setting the axis title in powerpoint reveals the default text of 'Axis Title'
I did some tracing and the values appear to save in the local object, they seem to be written with the $objWriter->writeElement('a:t', $oAxis->getTitle()); in PhpOffice\PhpPresentation\Writer\PowerPoint2007\PptCharts
but after that I don't know what happens...