The grid is 6x5 and there are no paylines. Instead, scatter pays mean that eight or more matching symbols landing anywhere award a prize, with the provider listing up to 50x in the base game for that. When a win lands, the winning symbols are removed and new ones fall into the gaps. That is a tumble, and it can chain: the same spin can produce several consecutive wins without you pressing anything. The important part is that a tumble sequence is a single paid spin, not a new bet each time symbols fall.
Because removals and falls are automatic, the maths of a session is not the maths of one tumble. The return to player figure of 96.48% is a long-run average across millions of spins on the published configuration. It says nothing about what a single tumble sequence, or a single session, will return. The same applies to the volatility label, medium-high, which describes the general shape of the payout distribution rather than a prediction for the next spin.