The entire purpose of changing the minimum age for The Stack from 13 to 14 was guest (parent) concern that the spread of 13-18 was too great. 18 year olds who have not graduated from high school or are between high school and college are allowed to participate.
As a general rule, if a 13 year old is within one month of turning 14, they are allowed to move up. As a less general rule, if the parents fuss enough, they get their way.
My suggestion would be to allow your daughter to start in Ocean Quest. Hopefully she will enjoy the age appropriate programming and can appreciate the teen program on a future cruise. However, if she finds that the 11-13 group is not suitable, you have a good reason to request that she be moved up.
You might want to check past posts/youtube videos, etc. as to what goes on in The Stack with relatively little supervision. My DD as a teen found it not to her liking to the extent that she would typically leave with a friend or two and find a calmer place to hang out.