Welcome to the TPG Community.
I checked your account and seen that the internet is already working. Is your ASUS RT-AC68U router connected to a modem/router? If it is, instead of using connection type PPPoE, you need to use the connection type Dynamic on your ASUS router since your modem/router is not on bridge mode.
If it's still not working, please contact ASUS technical support since they have the proper training with their device.
Keep us posted for any update.