The WPSSO Update Manager add-on is required to enable and update the WPSSO Core Pro plugin and its Pro add-ons.
The WPSSO Update Manager supports WordPress Network / Multisite installations and WordPress MU Domain Mapping.
Simply download, install and activate.
WPSSO Core Plugin Prerequisite
WPSSO Update Manager (aka WPSSO UM) is an add-on for the WPSSO Core plugin (Free or Pro version).