RTP is a long-run average; the house edge is the casino’s expected share: 96%...

https://www.random-bookmarks.win/rtp-is-a-long-run-average-not-a-session-promise-96-rtp-means-a-4-house-edge

RTP is a long-run average; the house edge is the casino’s expected share: 96% RTP = 4% house edge. Volatility describes how wins are spread out. In a short session, results can swing sharply, so your outcome may differ greatly from the average.