You can deploy your existing multi-site Drupal application as separate application instances. You will need to specify
Site directory on the 2nd step of new application deployment form. For example if you have a directory
sites/my-drupal-site/* you should specify
my-drupal-site. This directory will be used to locate
settings.php file and files directory. Also,
sites.php file will be created automatically inside
sites/ with mapping of all domains attached to this instance.