While busy with a large deployment of Office 365 for Education (150k users) at one of my clients I ran into this error after the initial 50000 users were created successfully:
You have reached the limit for the number of objects your company can create.
This happend in both my testing and production domains.
I also experienced the following response from PowerShell:
Unable to add this user because the total number of allowed objects has already been reached
As per http://support.microsoft.com/kb/2812409 these are DS quota limits that are enforced on all Office 365 tenants. I had to create a service request for each tenant with Microsoft to get the limit increased. For more information on how to request the DS quota increase click to http://support.microsoft.com/kb/2812409
