Can anyone help me out with a sideload error? Total xfer: 0.00x

I literally have a fresh out of the box Nexus 6P. I booted it, went through the whole set up but set it up as a new device. It offered to install the May security update but I declined.

I made it to the point where I picked "apply update from ADB" and it is waiting for the sideload.

When I type "adb devices", I get a string of numbers representing the device and the word "sideload"

I type in "adb sideload <name of zip>" and it returns: Total xfer: 0.00x

I did this on my last Nexus and I don't recall running into any problems. Does anyone know how to fix this?

Thanks!!!!