A DCS Redis instance can be access with or without a password. You can directly access a DCS Redis instance through a Redis client without setting a password. However, for security purposes, you are advised to set a password for authentication and verification whenever possible. The password must be set when you create the instance.
To change the Redis instance access mode, or change or reset a password, see Managing Passwords.

Is a Password Required for Accessing an Instance? How Do I Set a Password?