Once your Ottomatic Instance is deployed, you'll have access to your FileMaker Server through the standard Admin-Console.
If you are running FileMaker Server 19.4, the FileMaker Server Admin Console is available on port 16000. Your URL would look something like this:
With FileMaker Server 19.4 and greater, you will access the FileMaker Admin-Console through standard HTTPS:
Your credentials to the FileMaker Admin Console are in your welcome email.
For more information on using the FileMaker Admin Console, please see the Claris FileMaker documentation: https://help.claris.com/en/server-help/content/admin-databases.html