"You have to stay in the circle."
Translation:Tu dois rester dans le cercle.
avoir besoin de = "to need", while devoir = to have to, must
Avoir besoin de = to need, to feel the need of, to require, to request
Falloir & devoir = have to, must, need in the sense of obligation, no choice
Falloir is most used in the impersonal form: il faut que... whereas devoir is agreeing with the subject: tu dois...
Also a great explanation by Sitesurf here:
That is a correct translation.
Did you report it? Sometimes it is due to the people behind the scenes (mostly volunteers) not having added all possible, eligible and correct translations to the list of acceptable responses. The best way to alert them is, next time you get this sentence, translate it as you have here and, if your translation is rejected, click on report and check the box that says "My answer should be accepted".