Not authorized on admin to execute command mongoDB: Atlas M0 Free Tier cluster
Since you are using a hosted database service (MongoDB Atlas), many administrative commands are limited as they are either provided via the management interface or likely to introduce performance/stability issues.

The Atlas free tier has additional limitations since it is backed by a shared MongoDB instance. See: Unsupported Commands in M0/M2/M5 Clusters.


  "not authorized on admin to execute command {setFeatureCompatibilityVersion: \"3.4\" }"


The setFeatureCompatibilityVersion command is an administrative command used during upgrades. You cannot set this on Atlas Free Tier (M0) or shared (M2/M5) clusters.


  db.createUser(...)


User permissions and roles for MongoDB Atlas must be managed via the Atlas user interface or API. See: Add MongoDB Users.