Any tips for using an iPod Classic with Ubuntu 14.04.5 LTS?

I was just given an iPod Classic, 60GB. In looking at posts on these forums, there does not seem to be any posts since 2014 on using an iPod classic. All I want to do is transfer MP3 and WAV files from my PC to the iPod and listen to them. The File Manager in Lubuntu senses (sees) the iPod, but that appears to be the extent of it. So I am not sure how to proceed.

There is this link https://help.ubuntu.com/community/PortableDevices/iPod that talks about gtkpod, Amarok, Rhythmbox and Banshee. And this link ( https://help.ubuntu.com/community/Po...Devices/iPhone ) that seems to recommend Banshee for newer iPods. I tried to download gtkpod, Amarok, Rhythmbox and Banshee from the Lubuntu Software Center, but it says they all require trusting unauthenticated sources. So I cancelled the downloads/installations. I am not sure if I should download gtkpod, Amarok, Banshee or Rhythmbox given the lack of authentication.

QUESTION(S): Does anybody have any Idea or suggestions?

Thanks,

A.