Thank you for responding. I had given up on getting a response, and forgot about this thread. So I failed to update when my problem was finally resolved. I switched to a different ISP recently, and tried installing itch again. This time I had no trouble. And yes, the same anti-virus software was still turned on at the time.
My only guess as to what happened before was that my previous ISP was having trouble with the traffic redirecting during that phase of installation. So if anyone else reading this later is having similar trouble, consider taking your pc/device elsewhere to install itch.