That message comes from an old version of Soccer Engine. Earlier versions imported match data from a hosted data feed that was tied to CodeCanyon item support. That feed has been retired, and Soccer Engine 5.0.1 removed it from the plugin.
What to do: update Soccer Engine to the latest version (see Activation to get updates). The message goes away, and your competitions, teams, players and matches stay as they are. You can keep adding and editing them in the WordPress admin.