Events Manager user database

Hi,
I intend to use EM with a membership plugin. This plugin can use the roles and capability in WP-user database. When registering new users, it can syn up with WP-user database. EM also has optional required logined user for booking (that is our use case). My question is does EM use WP-user database to register new users or it uses its own user database? If it uses its own user database, is there a way to syn it with WP-User database?
Thanks in advance.