Limesurvey
Limesurvey is a top questionnaire tool https://www.limesurvey.org - available on their home page only as SaaS.
It is fairly simple to set up on a web server: https://github.com/LimeSurvey/LimeSurvey with php >= 7.0
LDAP is supported: https://forums.limesurvey.org/forum/search?query=ldap&childforums=1