If you have previously used the premium option to manually backup files to your icloud, there is no longer a need to manually restore them if you have Locker 4.0+. The app will automatically check for any files in the cloud every time it opens. As long as your phone is signed into the same Apple account that you backed up the files with, it will be able to retrieve your files. Note that if you deleted your iCloud files, or stopped paying for iCloud storage, this may prevent the files form being restored.
Note: The option to store new files in the cloud is no longer available in Locker 4.0. Instead you should use your iOS devices's iCloud backup service. Here's how you can check if you are already using it, or how to enable it.