One person builds this. Email gets read.
In the vault folder you chose when you first opened the app — on your device or in
your iCloud Drive. Open the Files app and look for the Cathode folder.
Deleting the app does not delete that folder.
If your vault is in iCloud Drive, install the app and point it at the same folder. Tap Restore purchase in Settings to bring Pro across.
Your receipt files are safe — only index.csv failed to parse, usually
because it was edited outside the app. Fix or remove that file and reopen; the app can
rebuild rows from the receipt files themselves.