In the SQL manager menu, you got:
List Databases and Users | List Users | Create Database | Create Database and User
So, if you created a database, you'll see it on the list, and you'll have a link at right side with "create user".
Add New User for Database: information_schema
Username: information_ (max 7 characters)
Host:
Confirm New Password: (random generator)
Confirm New Password:
So, if you created a database from user admin, database will be admin_name, and the users would be admin_name too.
Just create the pair, DATABASE AND USER, then fill that data on the Prestashop.