Auth0 authentication users can be presented with issues logging into SNB for various reasons, the usual step to resolve this is to use the Forgot your password button in the log in screen. On occasions they will not get the reset email and this is because they are not authorized for Auth0 for the tenant they are trying to access.
In order to get access to their tenant an admin user must log in to the tenant and via SNB Config include the user. The admin might need to log into the tenant using other URLs as a tenant could have various URLs based on different authentication methods.
The admin must use the add to signals authentication button to add the user.
When the user is successfully added they will see a massage stating that and they just need to save the changes.