Help with KeyCloak SAML

Your software
My Mautic version is: 3.1.0
My PHP version is: 7.3

Your problem
My problem is: Can’t properly connect KeyCloak SAML IDP.
Maybe someone can share IDP metadata file template (and KeyCloak client configuration).
I’ve getting in my KeyCloak instance this, but it is obv incorrect because isn’t have any auth realms.
My KeyCloak based on the

<md:EntityDescriptor xmlns="urn:oasis:names:tc:SAML:2.0:metadata" xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:ds="" entityID="">
    <md:SPSSODescriptor protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol" AuthnRequestsSigned="false" WantAssertionsSigned="false">
        <md:SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="" />
        <md:AssertionConsumerService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="" isDefault="true" index="1" />


Seems I have some progress, I found working template and Mautic trying to authenticate user via KeyCloak, but at end I again have an error that not explained in the logs absolutely.
I enabled debug mode via config/local.php but directory app/logs empty.

Mautic SAML configuration looks odd and abadoned, seems you need to have a lot of luck in order to set it up. No properly docs, no support at least one SAML provider by default, no logs.