looking at your logs it looks like you don't have jbpm console security realm defined in your standalone.xml file. Here is an extract of standalone.xml provided with jbpm installer
<security-domain name="jbpm-console" cache-type="default">
<authentication>
<login-module code="UsersRoles" flag="required">
<module-option name="usersProperties" value="${jboss.server.config.dir}/users.properties"/>
<module-option name="rolesProperties" value="${jboss.server.config.dir}/roles.properties"/>
</login-module>
</authentication>
</security-domain>
please take a look at the one that comes with installer to make sure you have all configuration required.
HTH