Protect new uploads
On the left side of the admin menu, you’ll see the Protect Uploads menu. After you click on it you will be able to upload any file from your computer and upload it protected. Please be aware you can only upload file extensions allowed by WordPress.
Protect already uploaded files
If you want to protect already uploaded files, go to the Media library, hover with your mouse on any file and click Protect.
The file will be converted to a protected upload file.
If you want to unprotect a file, go to the Media Library, hover with your mouse on any file and click Unprotect.
The file will be converted to an unprotected upload file.
If an user is trying to access an uploaded file which is not accessible for the user.