Correction after some tests

app/code/backup/Factory.php

@@ -6,14 +6,14 @@ class Factory
 {
     /**
      * @param array $config
+     *
      * @return BackupAbstract
      */
     public static function build(array $config)
     {
-        $class = array_keys($config)[0];
+        $class = __NAMESPACE__.'\\'.array_keys($config)[0];
         if (class_exists($class)) {
-            /* @var $instance BackupAbstract */
-            return new $class(array_values($config));
+            return new $class(array_values($config)[0]);
         }
         return null;
     }