You can apply a limit on the number of enrolled devices to an organization group (OG). Imposing such a limit helps you manage your deployment by preventing you from exceeding the number of valid enrollments.
This device limit can be placed on any type of OG (global, customer, partner). Once a limit is set at one OG, you are unable to set another limit anywhere in the same OG branch. You can set another enrolled device limit but only if you are setting it in a separate OG branch.
To define an enrolled device limit on your current OG, navigate to Groups & Settings > All Settings > Devices & Users > General > Enrollment. Next, select the Restrictions tab, and enable the limit under Set a limit for maximum enrolled devices at this Organization Group and below.
If this option is unavailable, check the parent OG (higher than the current OG) or a child OG (lower than the current OG). It is likely that an existing limit has already been defined above or below your current OG.