When advertising a no deposit casino bonus, many operators mention terms like “no-strings-attached” and “risk-free”, and to a certain extent, this is true because you’re not being asked to hand over any money.
However, there are usually stringent guidelines associated with the offers which may, for example, restrict how much you can win, how much you can withdraw, and what games you can spend your bonus on. So, you still get the free no deposit casino bonus, but you're not as free to do what you want with it as you might expect.
For example, you won't be able to withdraw your bonus without spending it first. You may also need to meet wagering requirements before you can withdraw any money.