When assigning a group an accreditation category, you can add a limit to that category for that specific group.
The limit only applies to approved applications. No limit applies to the number of people that can apply in that category.
You can set and change the category limits for a group in your event edition under Settings > Groups. Choose the group you want to change the category limits for.
You can raise or remove the limit at any time, but you cannot lower the limit below the amount of already approved applications.