1) Log into Service Desk Manager as Administrator user (ex: ServiceDesk)
2) Go to Administration > Options Manager > CA Service Catalog
3) Edit the casc_user and casc_user_password to right user and password. The default user set for casc_user is CASMAdmin
It's recommended to test the values set to casc_user and casc_user_password by logging to Catalog and EEM with this user.