What is the make and model of the router? Is it a Linksys, Netgear, Comcast supplied Linksys, or some other type? We can then go to the list and try the default user ID and password for that specific brand/model.
Sounds like it is asking for the default supplied password from the manufacturer which should have been provided with the router.
I do not use a router and have never helped set one up so if anyone else has ideas please advise.