If you're encountering an error code 16 for Google Play Music for Chrome and you're using Avast, you should disable the HTTPS scanning setting in Avast.
Avast > Setting > Active Protection > Web Shield > Customize > untoggle the "Enable HTTPS scanning" option.
Not the idea solution but a quick hack. It also took me a few tries of logging out of my google account, closing chrome (including the background running program), and turning off Avast to get it to work. Thanks arammos! Check out the source below for more details.
Source