The file never leaves your device. A PDF or Word resume is opened and read inside your browser; only the text you can see in the box is sent for scoring.
It is not stored. Your resume text is sent to the server, scored in memory, and dropped when the response is sent. There is no database, no account, and no file kept. Reload the page and it is gone.
It is not sent anywhere else. No third party sees it, and it is never used to train anything.
Work Scout never logs in as you. It reads public job board APIs only, and it will never ask for a password to a job site. Anything that does should worry you.
The postings come from other people. Pay, requirements and dates are whatever the employer published. Work Scout reads them, it does not verify them - always open the posting before acting on it.