BE 20 starts the VMware support from ESX 5.5
Workaround to backup the supported Guest OS and Application ---
Install BE 20, Install remote agent on the VMs that need to be backed up and backup the drives this way.
Please check BE SCL:
Only version 5.5 U3 and higher is supported.
This is because VMWare has ended support for older versions.
Your customer will need to upgrade VMware environment to use snapshot-based agent backups.