Hi,
You need to install Shibboleth where ILIAS is running. ILIAS is the SP (Service Provider) and needs Shibboleth for using with ADFS. Shibboleth on the ILIAS Server and ADFS on the other Server supports SAML2.0.
A guide to install shibboleth, you can find here:
https://www.switch.ch/aai/guides/sp/installation/
But you can't use the Guide from SWITCH for configuration it, this Guide is not for ADFS, it's for a special Authentication in Switzerland (SWITCHaai).
I don't know, if you need a sync. Perhaps you need a daily sync, to add new users automaticly to import to courses and groups. If a new user has no account in ILIAS, but a valid ADFS-Login, the user can log in, and the account will be generated automaticly. But if you would like to search for user and add them to courses and groups and you have no sync, you have to tell the new user to log in first.
For add new users by a daily cron job, we have a Plugin "Hub" which sync the user accounts.
Marcel