Calling constructor and assigning to object

I am testing some API code.

the SimpleClient.h header file contains the following:

class SimpleClient : public EWrapper, public EClientSocket {                    // The class

public:                                                                         // Access specifier
    SimpleClient(const char* host, int port, int clientId = 0);     // this is line 17          
    ~SimpleClient();                                                            

    EReader *reader;
    EReaderOSSignal signal;

/// begin virtual functions
// Event handling functions
    void tickPrice(TickerId tickerId, TickType field, double price, const TickAttrib& attrib) {};
    void tickSize(TickerId tickerId, TickType field, int size) {};
    void tickOptionComputation(TickerId tickerId, TickType tickType, double impliedVol, double delta,
        double optPrice, double pvDividend, double gamma, double vega, double theta, double undPrice) {};

inside Main.cpp

int main() {

  // Connect to TWS or IB Gateway
  SimpleClient sc("127.0.0.1", 1162709, 0);

  // Request the current time 
  sc.reqCurrentTime();

  // Sleep while the message is received
  std::this_thread::sleep_for(std::chrono::seconds(1));

  // Read the message
  sc.signal.waitForSignal();
  sc.reader->processMsgs();

  // Disconnect 
  sc.eDisconnect();
  return 0;
}

Inside SimpleClient.cpp there are definition outside the SimpleClient class:

SimpleClient::SimpleClient(const char *host, int port, int clientId) : 
  signal(1000), EClientSocket(this, &signal) {

  // Connect to TWS
  bool conn = eConnect(host, port, clientId, false);
  if (conn) {

    // Launch the reader thread
    reader = new EReader(this, &signal);
    reader->start();
  }
  else
    std::cout << "Failed to connect" << std::endl;
}

SimpleClient::~SimpleClient() { delete reader; }

When running int main() the following error appears:

error C2259: 'SimpleClient': cannot instantiate abstract class

SimpleClient.h(17): message : see declaration of SimpleClient

As I understand it there is the class SimpleClient and inside there is public access specifier which defines on line 17 SimpleClient(const char* host, int port, int clientId = 0); and ~SimpleClient(); they are public constructor/destructor and can be accessed from outside of the class.

inside Main.cpp. calling

SimpleClient sc("127.0.0.1", 1162709, 0);

is creating an object sc by calling the constructor as defined in the SimpleClient.h file and SimpleClient.cpp....?

In this case what exactly is going wrong and firing off error

error C2259: 'SimpleClient': cannot instantiate abstract class

SimpleClient.h(17): message : see declaration of 'SimpleClient'

Main.cpp(8,16): message : due to following members:
Main.cpp(8,16): message : 'void EWrapper::tickSize(TickerId,TickType,Decimal)': is abstract

Compiler Error C2259 link: https://learn.microsoft.com/en-us/cpp/error-messages/compiler-errors-1/compiler-error-c2259?view=msvc-170