The user-manager package is not included in the separate packages. It has its own link http://www.mikrotik.com/download/user-m ... 3.0rc1.npk
By the way, I also lost the subscriber and users/router a few times since upgraded to v3 beta version and once with RC1. Also got frequent reboot even the CPU load sits under 5% most of the time (This is installed in a P4 of 2.4GHZ and 500MB ram). Anyone else with similar issue?