In order to help we need more information like something from the logs. They are located here - C:\ProgramData\Veeam\Backup

Check here for the job logs and post more details cause the screenshot doesn't tell much.

It appears this appliance VM isn’t possible to backup (see here), unless you do 1 of 2 things → power down the VM for backup so a snapshot can be taken of the appliance; or, attempt to deploy the Veeam Agent for Linux in the appliance OS, which appears to be Debian-based according to the reddit thread.

This looks to me as not a VMware error, but something with the actual VM.  I’d double check by trying to manipulate the VM manually such as taking a snapshot and committing it, powering off the VM, etc. I’d assume that once you work through whatever issue you have happening here, it’ll be able to be snapshotted and backed up normally.