The 4.0 Community edition support SSL/TLS data encryption.
The encrypted backups and WiredTiger encryption at rest are available in the enterprise version of the product as well as other security features.
The enterprise version require a licences and I can contact you with the relevant sales representative if you want to.
MongoDB 4.2 introduced Field Level Encryption in the driver layer.
See our full security check list:
If you intend to run your instances in Azure I will strongly recommend using mongodb Atlas which have encrypted storage volumes and backups ,plus all the advantages of a managed service with best security measures (SSL, boc peering, auditing etc.)