Can I use PowerCLI to manage VMs hosted by VMware Player?
No. PowerCLI only works against vCenter or ESXi hosts.
Can I use it to manage VMs hosted by free ESXi hosts?
Yes, but the free ESXi license only allows you to perform read-only actions, i.e. things like Get-VM, Get-Datastore etc. You can't actually change settings with writing cmdlets (New-VM, Set-VM etc).
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