1. authelia
first, go to authelia, check 'remember me', and log in
your username is your email address
if you need to reset your password, hit 'reset password?' (from authelia, not jellyfin), and follow the prompts
2. jellyfin
go to jellyfin.cliny.net. this must be done via a web browser (eg firefox) because jellyfin SSO generally won't work anywhere else (eg android app)
hit 'sign in with SSO' (at the bottom)
check 'remember consent' and accept the consent request
then log in to other devices (eg android app) by using quick connect
3. jellyseerr
go to jellyseerr.cliny.net, and hit 'authelia'
check 'remember consent' and accept the consent request
pro tips
if you can't log in to jellyfin, delete the current cliny.net server from the app, and start again from step 1
to fix playback issues, wrong audio, subtitle settings, etc, go to your jellyfin settings and change things
to fix issues with movies/shows, you can report an issue in jellyseerr
updates from cliny
i disabled two factor authenication (so you won't require an authenticator app on your phone)