Due to an issue between Dolby Laboratories and Adobe, Adobe has pulled all versions that had any Dolby licensing included. So sadly many of the versions we users could access were removed from public downloads.
Search the forums for "Dolby" and "AC3". Due to that, Premiere Pro CC versions from 2014 through 2017.1.2 are no longer available from Adobe or anywhere else. The only version available of CC 2017 that's currently available is the 2017.1.4 version, which is the 2017.1.2 version with Dolby audio support removed. The only other older versions of Premiere that are available are the original 2013 release of Premiere Pro CC (aka version 7.0) and the CS6 version.