When a file is saved in Final Draft Vault, it is stored online in the cloud. That means any work you do on the file is saved to a remote secure server instead of your home computer or device. Because Vault is handled by a remote server, you can access your work at any time from any compatible device as long as you have internet access.
While writing in Final Draft Writer, your changes will automatically save in the Vault every time you stop typing, or you can also go to File > Save in the top left to ensure your changes are manually saved in the Vault.
When syncing your work between Vault and your home computer, the Sync Utility will make sure your changes are saved between Vault and your computer.
For more info on using the Sync Utility and syncing your existing work with the vault, click here:
How do I sync my existing work on my computer to Final Draft Vault?