The problem was solved already on the FreeBSD forums. I need to install gstreamer1-plugins-flac in order to play .flac etc. (This was not necessary for clementine for whatever reason....)

Hello, I guess I am very behind the times here, but FreeBSD recently removed audio/clementine-player from its supported packages, and so I installed audio/strawberry.

However, strawberry is not working for me, as I encounter the following error when trying to play music (flac):

GStreamer could not create the element autoaudiosink with name pipeline-2-autoaudiosink.

This is FreeBSD 13.0, and clementine had worked for me without issue....