Sound Juicer MP3/4

I’ve installed Packman repo & switched system packages then rebooted but not sure how to get Sound Juicer to play ball & rip to MP4:

“Your GStreamer installation is missing a plug-in.”

(Mother has new-fangled car radio with SD card media player…)

MP3 would appear to workz not MP4.

did you install
as I think aac is handled thru ffmpeg