RTP is the game’s theoretical average return over a very large number of plays;...

https://www.bookmark-suggest.win/rtp-describes-the-share-a-game-is-designed-to-return-over-time-the-house-edge

RTP is the game’s theoretical average return over a very large number of plays; the house edge is the share it expects to keep. A 96% RTP means a 4% house edge, not a promise that you’ll get 96p back from every £1 you stake