The in the mongodb.release.autoDownload section, the path listed to the mongodb-fetch utility is incorrect. The correct path would be /opt/mongodb/mms-backup-daemon/bin.

It should also be noted here that the backup daemon expects the tgz files to be extracted. I believe this is inconsistent with automation, and is not obvious here and very easy to get wrong. mongodb-fetch would do the right thing, but is in most cases not useful since the server will not have internet access for mongodb-fetch to work, e.g. the files would be manually copied to the server via some other means.