There is a Drupal Cloud limitation regarding granting permissions to accessing the sites file system.
By default the Content managers do have access to the File Browser; however this is because Content Managers have the
'Node: Bypass content access control ' permission set. If there are restricted roles defined, like Content Editor who may only edit certain content types, they will not be able to browse the file system to insert images of files. It is clearly undesirable to have to grant them such a broad permission.
In non Drupal Cloud, where ICME module configuration is available, more granular permissions to access the file system can be set.
Example: In Drupal Cloud unless you are a Content Manager,
results in
However if you define an image field ( or a file field) in the content type.
This will provide a 'Content Editor' who only has sufficient permission to edit that content type, the ability to upload images/ files and insert them in the body of the content.
Define image and/or file fields but set the display settings for these fields to ' hidden'
You can specify in the field definition: