I was trying to setup this blog but I kept being sent to the login on another website that I setup. The link was hard-coded into my WordPress setup, I didn’t know what to do with that. If you are having the same problem and are running a Linux server, run:

# Install WordPress CLI
sudo apt install wp-cli
# Replace the URLs.
wp search-replace 'oldsite.com' 'newsite.com' --skip-columns=guid

Problem solved. If your problem is more nuanced then mine, check out this article: https://wordpress.org/support/article/changing-the-site-url