a) In Wekan standalone version it's possible to disable self-registration in Admin Panel. There is inviting users, user permissions Admin/Normal/Comment only, but not user management yet:
Wekan is pretty much fully community contribution-driven. So the answer for it not having it's own AD/LDAP support at this point is that nobody has seemed interested in actually doing it and submitting a PR.
Wekan is available on many platforms: https://github.com/wekan/wekan/wiki/Platforms
a) In Wekan standalone version it's possible to disable self-registration in Admin Panel. There is inviting users, user permissions Admin/Normal/Comment only, but not user management yet:
https://github.com/wekan/wekan/wiki/Features#authentication-...
and in next version it's possible for user to change password: https://github.com/wekan/wekan/blob/devel/CHANGELOG.md
b) In https://sandstorm.io version there is already user management, Google/GitHub/LDAP/SAML authentication etc:
https://discourse.wekan.io/t/sso-passing-variables-through-u...
Newest version of Wekan is coming to Sandstorm in near future, progress is at:
https://github.com/wekan/wekan/issues/799