What is ambrosia audio? won't install

I just upgraded to yosemite and a message appeared that there was no support for ambrosia audio and the this is necessary for mac audio.

It asked permission to download and install and I said yes. When it said a restart was required to complete installation I hit restart. However, when I signed in to my Mac I got the SAME message that I needed to install Ambrosia audio. I repeated the process. What is going on and how do I fix it?