Maybe you should install oscam-emu, not a oscam stable, or press blue button on freeserver (Menu), and install Last Oscam/Ncam update IPK/DEB .
the only way is to install oscam from blue button in freeserver plugin. but oscam in openpli7.2 cant be installed from freeserver. in openatv6.3 all ok but in openpli7.2 it cant