So what I did was use Chrome's F12 developer tools to manually get the token. It's stored in something called callback. Then I clicked the "Enter Token Manually" button and entered my token, but nothing happened, it just stayed stuck on the same page. However, when I then went to https://taproom.cider.sh/oauth/itch, I could see a license page and was able to click the button to give Cider access.
