New router won't connect to the internet

I am in the position of not knowing what I don’t know, hence my request for guidance here.  I have CenturyLink fiber internet (1 mbps) service at my home.  The modem provided by CenturyLink is a nondescript unit.  In case it makes any difference, the sticker on the back says:

324 4th Gen

2POTS/4GE ONT

I’m trying to replace my existing wireless router, a CenturyLink C3000Z, with a Netgear Nighthawk RAX45.  As the directions enclosed with the new router suggest, I’m using the Netgear Nighthawk app in my attempts to complete the installation.

During the installation process, the new router is “found”, and my mobile device connects to the router.  However, the router is not able to automatically connect to the internet.  I have tried to connect manually using PPPoE and static IP (the two options the app gives me) to no avail.

My guess is that I need to change some sort of settings on the modem to be able to connect successfully.  While I know how to access the modem via my desktop computer and should be able to change the settings (I’ve looked, and it seems fairly intuitive), I have absolutely no idea what the settings should be so the modem and my new router can communicate.

Am I on the right track here?  Does anyone have guidance for how I can accomplish this task?  Any assistance you can render would be greatly appreciated.