You may need to create an app-specific password for Gmail in your Google account.
Login into your Google account, go to Security, then App passwords (you have to have 2-step verification turned on for Gmail, otherwise Google makes this setting is unavailable). Then under Select app choose Mail, select your device and press Generate. Your new password should appear in a new window. Copy and save it somewhere, because Google won't show it again. Then follow Google's instructions to complete the process. If at some point in the future you no longer need that password, you can go back to the App Passwords page and delete it.
That said, NetWorx has a new release coming very soon. It will have an automatic option for these settings.