RTP estimates the share of stakes a game returns over a very large number of...

https://rowansnewthoughts.quantlynix.com/posts/what-s-the-difference-between-house-edge-and-casino-profit

RTP estimates the share of stakes a game returns over a very large number of plays; it is not a promise about one session. A 96% RTP means a 4% house edge on average over time