CAS delegated authentication with OAUTH2.0 not working - authentication

Question

I was trying to add an oauth2.0 authentication provider in our cas (v6.1.x). But I was getting the following error.
2020-11-15 10:03:30,675 INFO [org.apereo.cas.web.flow.DelegatedClientAuthenticationAction] - <Credentials are successfully authenticated using the delegated client [OauthClient]>
2020-11-15 10:03:36,492 ERROR [org.apereo.cas.authentication.PolicyBasedAuthenticationManager] - <Authentication has failed. Credentials may be incorrect or CAS cannot find authentication handler that supports [ClientCredential(credentials=#OAuth20Credentials# | code: c.lKObb15ip36uiWfOYaTXEfQ | accessToken: com.github.scribejava.core.model.OAuth2AccessToken#5ca28902 |, clientName=OauthClient, typedIdUsed=true, userProfile=null)] of type [ClientCredential]. Examine the configuration to ensure a method of authentication is defined and analyze CAS logs at DEBUG level to trace the authentication event.>
2020-11-15 10:03:36,509 ERROR [org.apereo.cas.authentication.PolicyBasedAuthenticationManager] - <[OauthClient]: [id cannot be blank]>
2020-11-15 10:03:36,513 INFO [org.apereo.inspektr.audit.support.Slf4jLoggingAuditTrailManager] - <Audit trail record BEGIN
=============================================================
WHO: NotYetAuthenticated-e111ad8e-8e6f-4edd-9de7-d2eae5040704
As you can see the credentials are successfully authenticated. After that redirected back with unauthorized access on the browser UI with the above error.
The properties I used for delegated authentication is given below:-
cas.server.name=http://localhost:8080
cas.server.prefix=http://localhost:8080/cas
cas.authn.pac4j.oauth2[0].id=${CLIENT_ID}
cas.authn.pac4j.oauth2[0].secret=${CLIENT_SECRET}
cas.authn.pac4j.typedIdUsed=true
cas.authn.pac4j.principalAttributeId=email
cas.authn.pac4j.name=OauthClient
cas.authn.pac4j.order=0
cas.authn.pac4j.lazyInit=true
cas.authn.pac4j.oauth2[0].autoRedirect=false
cas.authn.pac4j.oauth2[0].principalAttributeId=email
cas.authn.pac4j.oauth2[0].enabled=true
cas.authn.pac4j.oauth2[0].authUrl=${AUTH_URL}
cas.authn.pac4j.oauth2[0].tokenUrl=${TOKEN_URL}
cas.authn.pac4j.oauth2[0].profileUrl=${PROFILE_URL}
cas.authn.pac4j.oauth2[0].profileVerb=GET
cas.authn.pac4j.oauth2[0].scope=profile,email,roles
cas.authn.pac4j.oauth2[0].clientName=OauthClient
Thanks in advance.