RTP is a long-run average, not a session promise: 96% RTP means a 4% house edge...

https://delta-wiki.win/index.php/What_Does_Expected_Value_Mean_in_Casino_Games_in_Plain_English%3F

RTP is a long-run average, not a session promise: 96% RTP means a 4% house edge over time. Volatility describes how uneven results can be. In a short session, you can finish well above or below the average.