Username and Password
This is out "out of the box" authentication provider - when you first sign up for Zepl, you created a Account username and Zepl password. When you have set Username / Password authentication set for your organization, team members can reset their passwords with the "Forgot your password".
Many teams find this to be sufficient for their security needs, especially if they are a small organizations that have not invested in a SSO provider. You can always restore to this form of authentication if anything goes wrong with your primary SSO provider.