Hi
The mpd_oled repository includes all the old mpd_oled code, and the last change that included support for Volumio 2 is
Volumio2: build last version of cava with bundled libiniparser · antiprism/mpd_oled@3de8a17 · GitHub
However, Volumio 2 is unsupported by Volumio and towards the end of its life it had a broken compiler, which meant mpd_oled could no longer be built on it
Cannot install build-essential package
I therefore stopped supporting mpd_oled on Volumio 2.
If you want to run mpd_oled on Volumio 2 you could, maybe, build binaries on Raspbian Jessie, and then copy the various mpd_oled binaries and scripts to the Volumio 2 machine.
Adrian.