Currently, Tabula collects no information regarding the behavior of users in app.
If the Tabula team begins collecting anonymous usage data, for the purposes of improving the app, users will be notified in the update notes of the relevant app store updates, and this document will be modified to reflect the exact scope of information collected, and how it is used.
Tabula uses iCloud Drive to sync documents between macOS and iOS devices. Tabula exclusively uses this service to sync documents, and does not collect information regarding other iCloud containers, or any personal information related to users' iCloud accounts.
Users on macOS can simply save and open documents from a non-iCloud folder to opt-out of this feature. Users on iOS can disable iCloud sync (and use local storage to save and load documents) in the Settings app under Tabula.
If you've chosen to share crash reports with 3rd party developers, then the Tabula team will be sent an anonymous crash report if (heavens forbid) you experience a crash. These reports contain relevant information to aid in reproducing and fixing the issue.