you don't need to develop any login page or components for login and creating account of the user in AEM.
AEM Supports SAML 2.0, In which you need to configure IDP details, certificate, user profile properties mapping with SAML assertion, User group assignment etc.
Once SAML configuration will be done and the path that you configured for SAML authentication will be accessed. (suppose /content)
SAML redirect will happen and IDP login page will be opened where once user provides valid credentials then SAML assertion response will be send to AEM (Service Provider). AEM will read the response and create the user account with mapped profile properties and assign the group as well if that is also configured in SAML configuration.
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