RTP is an abbreviation for “Return to Player Rate” In other words, it's the machine's payout rate.
RTP describes the percentage of bets a game pays out to players over the long term.
The average RTP displayed is related to the machine, not the player: a machine with an RTP of 96% doesn't mean you'll get back €96 on €100 played.
This should be viewed as an average taking into account all players over millions of spins.
For example, if X players play €100, then on average €96 will be paid out to all of these players: some will receive more and others less.
You can find the RTP percentage for each machine by consulting the Information section for each machine.
May luck be with you!