When do I need to download agent and how many agents do I need to download when implementing backup jobs?

For VM backup, Vinchin supports image-based agentless backup. For VMware Vsphere and Huawei FusionCompute KVM, it is directly connected with Vinchin server after you filling in the account information. For other virtual platforms, you just need to download a plug-in for connecting Vinchin with the virtualizations. 

For physical backup(file, database, server), it is agent-based backup, but you just need to download our light-weighted three in one agent once, then you can do each type of backup jobs smoothly. 

For NAS backup, it is agentless backup. NAS device can be directly added to Vinchin via CIFS or NFS protocol.