I still haven't gotten anywhere with this. Here's what I've tried so far:
1) modifying First Broker Login flow as follows -
Review Profile - disabled
Create User If Unique - alternative
Handle Existing Account - alternative
everything under Handle Existing Account that can be disabled I have disabled
Result: I authenticate with the remote SAML server but my local Keycloak server displays an error screen saying "Invalid username or password".
2) created a custom authentication flow containing the following -
Create User If Unique - alternative
A custom authenticator class with an authenticate method that just calls the success method of the AuthenticationFlowContext.
Result: I authenticate with the remote SAML server but my local Keycloak server displays an error screen saying "Invalid username or password".
As always, any suggestions would be greatly appreciated.