New RouterOS v4 doesn’t include the new User Manager by default, therefore you need to install it with this test package:
4.6
MIPS-BE http://mikrotik.com/download/userman-test-4.6-mipsbe.npk
MIPS-LE http://mikrotik.com/download/userman-test-4.6-mipsle.npk
PPC http://mikrotik.com/download/userman-test-4.6-ppc.npk
X86 PC http://mikrotik.com/download/userman-test-4.6.npk
4.7
MIPS-BE http://mikrotik.com/download/userman-test-4.7-mipsbe.npk
MIPS-LE http://mikrotik.com/download/userman-test-4.7-mipsle.npk
PPC http://mikrotik.com/download/userman-test-4.7-ppc.npk
X86 PC http://mikrotik.com/download/userman-test-4.7.npk
4.9
MIPS-BE http://mikrotik.com/download/userman-test-4.9-mipsbe.npk
MIPS-LE http://mikrotik.com/download/userman-test-4.9-mipsle.npk
PPC http://mikrotik.com/download/userman-test-4.9-ppc.npk
X86 PC http://mikrotik.com/download/userman-test-4.9.npk
4.10
MIPS-BE http://download.mikrotik.com/userman-test-4.10-mipsbe.npk
MIPS-LE http://download.mikrotik.com/userman-test-4.10-mipsle.npk
PPC http://download.mikrotik.com/userman-test-4.10-ppc.npk
X86 PC http://download.mikrotik.com/userman-test-4.10.npk
4.11
MIPS-BE http://mikrotik.com/download/userman-test-4.11-mipsbe.npk
MIPS-LE http://mikrotik.com/download/userman-test-4.11-mipsle.npk
PPC http://mikrotik.com/download/userman-test-4.11-ppc.npk
X86 PC http://mikrotik.com/download/userman-test-4.11.npk
4.13
http://www.mikrotik.com/download/share/userman_test_4_13.npk
http://www.mikrotik.com/download/share/userman_test_4_13_mipsbe.npk
http://www.mikrotik.com/download/share/userman_test_4_13_ppc.npk
http://www.mikrotik.com/download/share/userman_test_4_13_mipsle.npk
4.16
MIPS-BE http://www.mikrotik.com/download/share/userman_test_4_16_mipsbe.npk
MIPS-LE http://www.mikrotik.com/download/share/userman_test_4_16_mipsle.npk
PPC http://www.mikrotik.com/download/share/userman_test_4_16_ppc.npk
X86 http://www.mikrotik.com/download/share/userman_test_4_16.npk
All version changelog:
http://wiki.mikrotik.com/wiki/User_Manager/4#Changelog