Near the bottom of that page, you will find "Resources and Shopping Help". Under that, you should find the assistance you need.
AFTD stands for Advanced file type device. This type of NetWorker device is used for backups to a disk device. Please refer to this document for additional information, as well as the NetWorker Administrator guide.
EMC® NetWorker Best Practices for Backup-To-Disk devices in NetWorker 8.0