Hey @ESN / Chris
The config.php file is required for the app to be able to communicate with the database. If you don't have it from your old install, you can create your own with the following template:
$dbhost = 'localhost';
$dbusername = 'itflow-db-user';
$dbpassword = 'itflow-db-pass';
$database = 'itflow';
$mysqli = mysqli_connect($dbhost, $dbusername, $dbpassword, $database) or die('Database Connection Failed');
$config_app_name = 'ITFlow App';
$config_base_url = 'URL';
$config_enable_setup = 0;
$repo_branch = 'master';
$installation_id = 'make-something-up-asdasn983na';