[keycloak-user] Unable to change login theme to other than base

Dear all. We are testing Keycloak as SAML2 gateway to some both external and internal systems we are to integrate with. We downloaded and configured Keycloak server (standalone) version 6.0.1, created a new realm, and for the initial tests add some clients running on Tomcat. We are able to authenticate to those clients via SAML2 protocol, but the problem is that I would like to configure the login page for them to be the one provided by the corresponding realm theme, and get only the base theme’s login page. Did I misunderstand the documentation (3.6 Theme Selector -> “By default the theme configured for the realm is used […]”)? Could any of you figure out what I am doing wrong? Many thanks in advance for the help. Best regards.