RBAC (roll based access) in a cluster for node.js sdk

So I’m using the 3.0 version of the sdk and seems like the docs are incomplete or still in-progress. I’m trying to enable role-based bucket access but not able to achieve this. I will really appreciate if someone can help who has done this.

My connection string looks like this.
COUCHBASE_CLUSTER_ADDRESS=couchbase://34.X.X.168:8091,34.X.X.199:8091,34.X.X.93:8091

And this is how the error comes:
error Data : {"name":"Error","message":"parent cluster object has been closed","stack":"Error: parent cluster object has been closed\n at Connection._maybeBFwd (/app/node_modules/couchbase/lib/connection.js:226:13)\n at Connection.store (/app/node_modules/couchbase/lib/connection.js:273:10)\n at /app/node_modules/couchbase/lib/collection.js:558:18\n at /app/node_modules/couchbase/lib/promisehelper.js:30:7\n at new Promise (<anonymous>)\n at Function.wrap (/app/node_modules/couchbase/lib/promisehelper.js:29:12)\n at Collection._store (/app/node_modules/couchbase/lib/collection.js:557:26)\n at Collection.upsert (/app/node_modules/couchbase/lib/collection.js:630:17)\n at exports.upsertQuote (/app/helpers/upsertQuote.js:9:41)\n at Object.exports.addToQuote (/app/controllers/quoteController.js:134:42)"}