failed install via homebrew

[metropical]

tried to install with homebrew. fail. MacPro3,1 on High Sierra.

Installing Cask background-music
==> Running installer for background-music with sudo; the password may be necess
Password:
installer: Package name is Background Music 0.4.3
installer: Upgrading at base path /
installer: The upgrade failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.)
==> Purging files for version 0.4.3 of Cask background-music
Error: Failure while executing; /usr/bin/sudo -u root -E LOGNAME=fritz USER=fritz USERNAME=fritz -- /usr/sbin/installer -pkg /usr/local/Caskroom/background-music/0.4.3/BackgroundMusic-0.4.3.pkg -target / exited with 1. Here's the output:
installer: Package name is Background Music 0.4.3
installer: Upgrading at base path /
installer: The upgrade failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.)

any thoughts or assistance appreciated.