To use the MySQL Database Service, you must ensure that certain prerequisites are met. Firstly, you or your group must be granted the appropriate policies as described in Mandatory Policies to have the necessary permissions. Secondly, you need to create a tenancy and be able to sign in to it, as the tenancy is your dedicated space within Oracle Cloud Infrastructure. Lastly, creating a compartment to store your resources is required for organizing and managing the resources you'll use with the MySQL Database Service. Downloading the latest MySQL version or installing it on Oracle Cloud Infrastructure are not required steps for using the MySQL Database Service, as the service itself manages the MySQL instances.