Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello,
When the directory service quota is reached, a quota increase can be requested through Microsoft Support.
Unfortunately, as a community moderators, I don’t have access to the backend systems needed to increase the quota directly. I recommend contacting Microsoft Support and providing your Tenant ID, current quota usage, and business reason for the increase so the appropriate team can review the request.
For reference, you can also follow the guidance in Error (This company has exceeded the number of objects that can be synchronized) displays in a directory synchronization report.
I hope this information helps point you in the right direction.