According to the Nature Foundation’s website you need a dive tag to dive in *any* Sint Maarten waters. $3/day $15/year. But aren’t visitors to this park only snorkeling? https://naturefoundationsxm.org/diving-in-sint-maarten/register/

I don’t know who gave you the scolding, but of course it’s in Aqua Mania’s interest to have people think they can’t go out there on their own. Not sure how any one would actually enforce that though.