Beforehand make sure you followed all steps from here:

https://stackoverflow.com/a/78970091/15550211

Here is some code how I make my Async Connection with J-Link resp. OTK:

public class SessionHandler {
    private final AsyncConnection connection;
    private final Session session;
    


    SessionHandler() throws jxthrowable {

        System.loadLibrary("pfcasyncmt");
        System.out.println("pfcasync.dll, loaded");
        this.connection = pfcAsyncConnection.AsyncConnection_Connect(null, null, null, null);
        this.session = connection.GetSession();

    }
}