trying to set own wireless router for DU connection

Hi
I am setting D-LINK DSL-2730_U1 wireless N 150 (ADSL2+) router at my home in Dubai.
I have a DU wired connection at home in which they provided me 6742-A1-UK-ADU model and I am trying to replace with above D-link wireless router for wireless connectivity.
However, D-LINK modem during the installation process, asked me for “Username and password” provided by ISP for which I called ISP and they said we don’t have any credentials setup, which was weird.
So I read one forum and found that DU internet provides Router IP as 192.168.1.1 and
Username – Admin
Password- Conf

I logged into the du router on http:192.168.1.1 and credentials worked.
So I switched to D-LINK wireless and provided the same credentials however with that, D-LINK prompted that “confirm username and password “ with your ISP”
(I used PPPoe Option during installation process
)
I have attached the screenshot of Installation process
Any suggestions.