NMS300 Device Discovery Issues

Hello,

I am attempting to back up several Netgear switches of all different models (mostly GS728TP and GS510TP) via NMS300 1.7.0.4 and am getting stuck at the discovery phase.  Every netgear switch is returning a credential failure, even though I verified that the HTTP credential and SNMP community strings are both correct.  I did notice that when I authenticate to these switches in a browser, it does not ever prompt me for a username, and I am struggling to find what user I've logged in as so that I can cross check that as well.  Is it possible I should be using a username other than admin to authenticate and perform the device discovery?

Thank you.