Quick Play is how you play without organising anything: pick a game, you are seated at a table with space, and the game starts as soon as there are enough players.
No code, no invitations, no agreeing a time with anyone. If no table is open for that game, one is created and everyone arriving after you sits down with you.
No account needed either. If you have one, coins earned in these games go to your profile just as they would in a private room.
Once a public table has enough people, a short countdown starts before the deal to leave room for one more to arrive. And if that game has configurable house rules, no host decides them here: everyone votes for the one they want and the tally shows on each option.
Abandoning a public game in progress has consequences, because there are people on the other side waiting for you to play. The first time is only a warning; if it happens again, the Quick Play lockout climbs from 5 to 15, 30, 60 and up to 180 minutes.
Warnings expire: after a day of playing without walking out of anything, the count goes back to zero. And this only ever applies to Quick Play, never to private rooms with a code: what happens in a room you invited your own people to is between you and them.