PaperVault does not collect any data, and does not perform any network calls to any remote service. PaperVault author does not have access to your documents or anything you do with PaperVault. On macOS, PaperVault is sandboxed without network access.
As part of normal operation of the operating systems, encrypted data may be transmitted across the network, or directly to different devices through a cable or wireless ad-hoc connections. The features that do so are implemented by the operating system or third party software, and are not controlled by PaperVault author. Examples or this are backups, migrations to new devices, printing to networked printers or continuity camera. Read the Network section in the PaperVault security page for more details, Apple's privacy policy for details regarding iCloud and other services operated by Apple and the privacy policies of third part software in use that may affect privacy and data handling like third party backup software.