A friend decided to give it a try and so I recommended getting the app, but they got stuck when trying to make an account since they kept getting

Validation failed: Locale is not included in the list

I tried it myself and got the same error (mastodon.social). Tried googling around but only found one Reddit post from months ago about it.

Is the app not how people usually sign up? I thought it might be the most painless compared to "trust me and use this link"