This article, and the ones under it, are specifically about using MongoDB.com to host MongoDB databases.
Are you using the dokku plugin instead?
There are many hosting options for a MongoDB database; hosting on MongoDB.com is one, and hosting on the dokku servers using the Mongo Dokku plugin is another. If you are using the dokku mongo plugin, this article is not relevant to you. Be sure you know which MongoDB hosting solution you are using before reading further.
Articles about getting things done with MongoDB.com
- mongodb_new_database Setting up an account and a new database