Mongo: mongodump and the config database error
You don't have the required privileges for the config database.

See https://docs.mongodb.com/manual/reference/built-in-roles/ :


  readWriteAnyDatabase
  
  Provides the same privileges as readWrite on all databases except local and config. 
  
  userAdminAnyDatabase
  
  Provides the same access to user administration operations as userAdmin on all databases except local and config.
  
  dbAdminAnyDatabase
  
  Provides the same privileges as dbAdmin on all databases except local and config.


For mongodump, use the backup role. 


  The admin database includes the
  following roles for backing up and restoring data:
  
  backup
  
  Provides minimal privileges needed for backing up data. This role provides sufficient privileges to use the MongoDB Cloud Manager backup
  agent, Ops Manager backup agent, or to use mongodump to back up an
  entire mongod instance.


Specifics about mongodump https://docs.mongodb.com/manual/reference/program/mongodump/ : 


  Required Access
  
  To run mongodump against a MongoDB deployment that has access control
  enabled, you must have privileges that grant find action for each
  database to back up. The built-in backup role provides the required
  privileges to perform backup of any and all databases.