I suppose this PPA is not used anymore to install native UBUNTU openedx:
https://openedx.atlassian.net/wiki/spaces/OpenOPS/pages/146440579/Native+Open+edX+Ubuntu+16.04+64+bit+Installation However UBUNTU is not Debian and chances are that trying the above mentionned method to install Openedx on Debian will fail. It seems the recommended method recommended by Edx to run Openedx on other Linuxes is inside Docker: https://github.com/edx/devstack
