Microsoft decided not to put filter buttons on PivotCharts in Excel for Mac. Apparently, they think it's unnecessary clutter, what with having filter buttons on the PivotTable and slicers available now.
I did a quick check of the feature suggestion site, and wasn't able to find a feature request asking for these buttons. If you want to suggest that the buttons be included in PivotCharts, please make a request in the UserVoice forum. Thanks.