(That link should be
this instead - missing a colon.)
Basically, the error means that the type of your table variable is "NetworkTable*" (a pointer to a NetworkTable), while GetTable() returns a std::shared_ptr<NetworkTable>, which can't be converted to a NetworkTable* directly. The place you actually want to change is currently line 9 in your code, where you declare "table" - it should be "std::shared_ptr<NetworkTable> table;".