Hey @Carlos_Mostek, I marked your solution as answered. Thanks for the tip. I better reworked the solution to comply with the standard. Here is the solution:
FrontEnd
signUp(email) {
this.loginScreen.authorize({
login_hint: email || ''
})
}
Hosted Login
var lock = new Auth0Lock(config.clientID, config.auth0Domain, {
initialScreen: 'login_hint' in config.extraParams ? 'signUp' : undefined,
...