Spring oauth2 - Cannot login to /oauth/authorization - spring

Question

I'm trying to secure my REST app with OAUTH2, in this case with Authorization Code Grant. So basically i think that when trying to access the /oauth/authorize endpoint, i should get a login page (from my app) where the user should authenticate with my app in order to make the client app get the token in the redirect_uri. Is this correct?
My clients are in a DB, I have created all the tables Spring Security needs. In this case I have a client_id = test and authorized_grant_types "access_token,refresh_token,implicit,authorization_code"
This is my AuthorizationServer config
#Configuration
#EnableAuthorizationServer
public class AuthorizationServerConfig extends AuthorizationServerConfigurerAdapter {
#Autowired
DataSource dataSource;
#Autowired
#Qualifier("authenticationManagerBean")
private AuthenticationManager authManager;
#Override
public void configure(AuthorizationServerSecurityConfigurer oauthServer) throws Exception {
oauthServer.tokenKeyAccess("permitAll()").checkTokenAccess("isAuthenticated()");
}
#Override
public void configure(ClientDetailsServiceConfigurer clients) throws Exception {
clients.jdbc(dataSource);
}
#Override
public void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {
endpoints.tokenStore(tokenStore())
.authenticationManager(authManager);
}
#Bean
public TokenStore tokenStore() {
return new JdbcTokenStore(dataSource);
}
}
The resource server (in the same app) is
#Configuration
#EnableResourceServer
#EnableGlobalMethodSecurity(prePostEnabled=true)
public class ResourceServerConfig extends ResourceServerConfigurerAdapter{
#Autowired
DataSource dataSource;
#Override
public void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.antMatchers("/api/**").access("hasRole('USER')");
}
#Bean
public TokenStore tokenStore() {
return new JdbcTokenStore(dataSource);
}
#Override
public void configure(ResourceServerSecurityConfigurer resources) throws Exception {
resources.tokenStore(tokenStore());
}
}
Last, my general SecurityConfiguration sets the security levels for the web app part of the application and not for the "/api/**" part. I'm trying with PostMan to send a post request to http://localhost:8080/oauth/authorize with this parameters: client_id=test redirect_uri=http://test.com response_type=code but i'm getting this error
User must be authenticated with Spring Security before authorization can be completed.
I thought i should get a login window where the user should authenticate
what i'm doing wrong?