In the appstore there is a Mx8 compatible version: https://appstore.home.mendix.com/link/app/24/Mendix/LDAP-Synchronization-module
You might need to upgrade that one to Mx8. Do so by creating a new project, import this module and then upgrade this project to Mx8. You can then export the module and import that in your existing Mx8 project.
Regards,
Ronald