What notifications does the app send, and how do I change them?

There are three kinds: Outbid, Auction won, and News and offers. News and offers are promotional and are off unless you turn them on. Choose which you want in Settings → Notifications. Your choices are saved to your Creta account, so they follow you to other phones and Creta apps.

The app only asks for notification permission after your first bid, which is when notifications become useful. Past notifications are in the inbox behind the bell icon at the top of the app.