The first and most obvious way websites can detect cheaters is by analyzing the games being played. This means that they will look at the accuracy and strength of each move, as well as the time between moves, to gauge if the person is cheating.
Their system does this in an automated way and there's nothing you can do to prevent it.
Ban Decision Factor: High
Your gameplay behavior will be heavily scrutinized if you're ever suspected of cheating.
Typically, these kinds of bans are not automatic. If their system detects that you're playing too strong, it'll send a notification to a mod or admin who will manually review your account and make a judgement call.
To avoid this kind of detection, you'll want to play in a way that doesn't make it obvious you're cheating.
Reduce the engine settings so it plays weaker (see the recommended engine settings).
Also, don't always play the top line. Play 3rd or 4th line moves, or play something else entirely that the engine doesn't suggest. Make blunders because the engine doesn't always make good blunders.
If you're using auto-play, don't use a fixed delay or too small of a delay, otherwise their system can easily see that you're cheating. Use a random delay of at least 500ms.