How do I approve my iphone from my pc?

My phone has rebooted 3 times in the last week. And I have to manually reset it as I don't have a Mac to just update it automatically. THe last step it always asks me is to "APPROVE THIS PHONE" from one of my other devices signed into the iCloud. I'm on my PC trying to do this and there is nothing that shows me how to do it. I can see that my iphone is up and running. But the Approve this phone and constant messages to complete this is still there. I think that's why this thing has rebooted 3 times because I don't/CAN'T finish that last step.