Andi, you need to deploy the the VSM OVF via vCenter and not directly to ESXi.
(FYI your question should've gone under the vSphere section)
Don't download on esxi,download using vcenter web client.
download the vcenter server virtual appliance, then manage the hosts that you want to deploy N1KV, in one them deploy ova to, this will be the supervisor Module VM , then prepare the esxi hosts with vibs of N1KV from VEMs.
check detail here:
prior to deploy remember to create the vlans for control, management & packet.