Hi @AskMe-Solutions team,
As @pahofmann mentioned you would not be able to set a quota limit for host units at the management level. If you would like to capture that information and as a workaround push an event to trigger a problem when such limits are reached per management zone, you can meet those requirements.
What I mean is to use the following API and filter per management zone:
Later calculate the sum of all the "consumedHostUnits" and with a simple condition function, trigger the following API to push the events to either all/selective main entities in the management zone to open a problem with some context like - 'Management Zone Host Unit Quota reached'
Like this, you can automate the requirement and let the script run on a regular interval to monitor the limit as per your need.