Welcome to the Centrify forums.
This thread contains the info you need: https://community.centrify.com/t5/Centrify-Express/AD-Time-sync/td-p/29055
Tip: when facing an issue with centrify, you can leverage the searchable features of the community, also all our docs are indexed by search engines as well.
e.g. " ntp site:community.centrify.com" or " ntp site:docs.centrify.com" yield relevant results.
Also, make sure that there is not firewall (or intermediate device) blocking communications over NTP.
The command /usr/share/centrifydc/adcheck [your-domain] --test ad | grep TIME checks time sync.
Also adinfo -y all will give you informationa about time.
Tip: ntupdate may not be the tool to use.
R.P