Yes, that is correct. You will need to configure the additionalSignUpFields on the Classical Universal Login experience. It will not work with the New Universal Login experience.
First, I recommend checking this FAQ to learn more about configuring additional sign-up fields on the Classic Universal Login experience.
And then to edit the description, you can change the lock configuration object in the custom login page script, specifically the languageDictionary for the signUp object.
Please let me know if you need further clarification or help.
I did what I could, having to stuff text where it doesn’t really belong. Will have to see if it’s sufficient for my client; they may not like it.
A description field would have been perfect, but there isn’t one.
databaseSignUpInstructions would have good too, but setting this one has no effect.
success → signUp would also have been good, but this message never shows up. After submitting the sign-up form, the user is directed right back to the app.
How are these two above supposed to work?
Are there plans to make this stuff work with the New Universal Login experience?
Allow me to offer one other alternative that may work for you. One workaround would be to use the New Universal Login experience for your application so that you can have a description field on the sign-up page that you can customize.
Then to collect the additional sign-up fields, you could redirect your users to a separate page that you host to collect this information. Once that is complete, you can resume the authentication flow and send the user back to the callback URL. This can be accomplished using Redirect Actions.
Ultimately, there isn’t a way to use both the additionalSignUpFields and description field features at the same time.