If so, I’m getting:
“This extension has not been marked as being compatible with your version of SketchUp. You may experience usability issues if you try to install this extension.” (I’m using SU v2016, btw.)
Authors of extensions in the Extension Warehouse mark which SketchUp versions their extensions are known to be compatible with. Getting this message soon after release of a new version usually means the author has not yet updated their EW info. API changes from 2015 to 2016 were limited enough that most extensions will work fine.