This seems to be working now, the error is a wee misleading. The code was correct. The URL was incorrect and was changed to (or leave blank):
const url = "sharedprod.braincloudservers.com";
...
brainclouds2s.request(global.s2sContext, {
service: "group",
operation: "SYS_CREATE_GROUP",
data: groupData,
});
})
