Hello, in my opinion those are two things mixed together.
1) "No deposit bonus" means you do not have to deposit in order to get the bonus and play it. However if you win, in most cases in order to be paid out, you need to register your payment option in the casino. This is usually done by depositing the same way you aim to withdraw your money; those deposits are based on the rules and subject to wagering requirements.
So, it is just the necessary stop for the lucky winners.
2) "play now deposit later" bonuses allow you to play without a deposit; however, to meet the bonus wagering requirements, you are required to deposit and wager with your money. Under such circumstances, though, if you again manage to win and fulfill the wagering, since the deposit was done already, there is usually little need for the additional verification deposit.
I hope it helps. Feel free to paste here the concrete bonus term; we can all take a look at it together.
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