Hello @Casey Park ,
welcome to this moderated Azure community forum.
Yes the limit is set to 200 as documented by Microsoft so this is the limitation in IoT Central.
There is no configuration setting to support more users.
That said, sometimes Microsoft just picks a number because they expect this is the best fit, not a technical limitation (this is called a soft limit).
I recommend creating a support ticket, explaining your use case and asking for lifting the soft limit if this is possible.
If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.