I’m running a ghost 5.44 through yunohost on a DO droplet. My users simply cannot subscribe. The error message they are seeing says something about a failure to send a magic link.
Are you using mailgun ? would you please be kind enough to share your config.production.json (minus passwords) ? I’m a total newbie in the .json area. I can only edit mine through semi blind copy/pasting.
Perhaps you could share your your settings. It would seem that transactional email isn’t working, so please confirm what you have done, e.g., setup DNS and correctly configured Mailgun.