Sign in with your ATmosphere account
Your Bluesky or other AT Protocol handle. You will authorise this site on your own PDS, and your fediverse account here will be paired with it.
Your PDS will ask you to grant identity access. This site uses it for one thing: adding your account here to your DID document, and only when you ask, with a code your PDS emails you. You can refuse it and still sign in.