How do I update to 7.1.1?

I bought an unlocked factory reset Nexus 6P yesterday and want 7.1.1 on it, and it currently has 7.0. I downloaded an OTA file for 7.1.1 and followed the recovery mode steps but when I get to the part to install it from my storage(and yes, I have a copy of the download in both the download and internal storage locations) my only options are "install from SD card" and "install from ADB" and neither work. I also enrolled my phone in the Android Beta program last night and while it has not been 24 hours yet I nevertheless refresh the update checker frequently and it always says the phone is up to date, so maybe I'll get it closer to the 24 hour mark? I'm willing to rooting the 6P if need be (as long as there is a method that is simply to unroot/flash stock firmware should I choose to), I just want the new features and best performance.