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,
  });
})

I'm trying to follow the basic structure of an S2S call via node as demonstrated here but I get back rafts of Java stack with this at the top:

"status_message":"Processing exception: com.braincloud.common.ProcessingException: Invalid app ID.\

and as far as I can tell I have set these values appropriately. I even tried using a numeric type for the ID. Any idea what I'm doing incorrectly?

Code:

const brainclouds2s = require("brainclouds2s");

const appId = "1***1";
const serverSecret = "e2******27";
const url = "internal.braincloudservers.com";
const serverName = "*****"

const groupData = {
    name: 'TestGroup',
    groupType: 'StudentGroup',
    isOpenGroup: false,
    acl: {
        member: 1,
        other: 0
    },
    jsonOwnerAttributes: {},
    jsonDefaultMemberAttributes: {},
    jsonData: {}
}
global.s2sContext = brainclouds2s.init(appId, serverName, serverSecret, url);
brainclouds2s.setLogEnabled(global.s2sContext, true);
brainclouds2s.request(global.s2sContext,{
    appId,
    serverName,
    serverSecret,
    service:'group',
    operation:'CREATE_GROUP',
    data: groupData})