The username is "cosmos" (without quotes).
The password is "cluster10" (without quotes).
Note that the default password is “raspberry”, but this should have been changed. If you are using a fresh install (so not a pre-installed drive or a cloned image) and still have the default password, you should change it. Otherwise, anyone could log in if the IP address is worldwide discoverable. You can change the password by running the following command on the RPi:
sudo raspi-config
Select option "1 System Options" and then "S3 Password". You navigate using tab and the arrow keys.