The CentralAuth extension for MediaWiki needs a separate database to setup and configured to store it’s data. By default, it will assume that there is a database named centralauth it can use, using the same credentials as the main database.
But you need to be careful and carefully follow the setup instructions to make this extension work.
For this particular issue, you need to create a new MySQL database through our panel, and configure CentralAuth to use that database. Please remember that all databases are prefixed with your account username, so you cannot have a database centralauth, but you can have if0_37169347_centralauth.
You may also want to go through this topic from a few weeks ago where we helped someone else setup that exact same extension. It’s quite an involved process, so you should definitely give it a look.