The official, supported way to install Metasploitable 3 uses Vagrant and Packer, which allows the target machine to be fully updated and customized.
Ensure the Network Adapter is set to Host-Only or Internal Network .
The site supplying most of the MP3 files to the Red Hot Jazz Archive pages on Syncopatedtimes.com is down and many links no longer work. You may find the original Redhotjazz.com and download all of the original RealMedia .ra music files on the WayBackMachine at Archive.org.