How much 'experience' do the players need? ALL they need to do is act in character, that's it! "I rush the goblin with my spear!" OK! The GM says "that's Hack & Slash since your spear can clearly engage the goblin before he can bring his little dagger to bear on you." What skill does that require? I mean, sure it helps of the player thinks "Gosh, I'm a dwarf fighter with a spear, I'm pretty tough, it's a good idea for me to fight!" but that doesn't even require system knowledge, just basic application of the logic of fictional position (which the GM is bound to honor). It's certainly no more demanding than any version of D&D where you would need to have a similar level of understanding of the strengths and weaknesses of your character (IE the same logic would suffice for 5e, right).
I've never understood the notion that there's something difficult about playing a PbtA. It is one of the least demanding and most obvious sorts of game for a player to grasp and requires ZERO system knowledge to play at a basic level of competence (It certainly doesn't hurt to have a good grasp of the rules, for instance the dwarf in the example above could Discern Realities instead, gaining a potential advantage and probably still engage with the spear, though it might depend on more details as to whether it poses any risk). Still, it's an exceedingly simple game, with far less intricate rules than 5e D&D.