Mastodon newbie protip: don't click the "remote follow" button. Just copy the user's URL and paste it into the search bar of your home instance, then click the follow button (the little icon of a person with a "+" on it).

Not only is "remote follow" slower and more awkward; it's a potential security risk, because a malicious instance could trick you into giving them your password (if you're not paying attention to the URL bar).