The username and password pair are casuser and Mellon in the default settings of CAS.
cas/application.properties at 6.4.x · apereo/cas
You can't perform that action at this time. You signed in with another tab or window. You signed out in another tab or…
This password is an analog from The Lord of the Rings in my opinion. While the fellowship are trying to reach Mordor, they find their way to the mines of Moria (khazad-dum), and they must open the secret door to enter it. It says “speak ‘friend’ and enter” on the secret door. This is a kind of passphrase. Frodo asks Gandalf that what “friend” means in elvish (elf language), and he gets the answer “Mellon”. When you say “Mellon” to the secret door, the gate opens.
Similarly, Mellon password must be given in order to enter the CAS server.