The Animation and Rigging Tool is not currently/officially compatible with Maya 2016. However, I found the error you have posted on Autodesk’s website here:
and it does not appear a major issue. You may want to post this on Jeremy Ernst’s forum thread as it may be something he could easily fix:
Animation and Rigging Tools: FAQ, Known Issues and Feature Roadmap
Meanwhile, I can verify that the A.R.T. does install on Maya 2015 -if you have this version available.