arduino create agent plugin installation problem

whenever i try to install the arduino create agent plugin on my mac it stops at about 75% gives some jumbled error message that doesn't make sense. Then the only option is "OK", so i click on that and it finishes installing. saying installation is complete, and i click finish. But arduino cannot locate the plugin and the icon that it installed does nothing. i'm so frusterated the arduino app i downloaded from sunfounder won't upload code to my uno board. I keep getting an innapropriate ioctl for device code. and without the arduino create agent plugin i can't upload from here either. hopefully somebody can help.