You should specify settings in your like this:

WEB3AUTH_USER_SIGNUP_FIELDS = ['email', 'username']

In the above example the following User model is used:

from django.contrib.auth.models import AbstractUser
from django.db import models
from django.utils.translation import ugettext_lazy as _
from web3auth.utils import validate_eth_address

class User(AbstractUser):
    address = models.CharField(max_length=42, verbose_name=_("Ethereum wallet address"), unique=True,
                           validators=[validate_eth_address], null=True, blank=True)

    def __str__(self):
        return self.username

Here’s a list of available settings:

Setting Default Description
WEB3AUTH_SIGNUP_ENABLED True If False, new users won’t be able to sign up (used in signup_view)
WEB3AUTH_USER_SIGNUP_FIELDS [‘email’] Specifies field to be used in signup form for a new User model
WEB3AUTH_USER_ADDRESS_FIELD ‘username’ Field on the User model, which has ethereum address to check against.