Not sure what you’re asking for here. All Peplink devices include licensing for InControl2 management in the first year (and for every year after that if you keep the device in warranty / buy IC2 subscriptions).
Or you can host a private InControl 2 appliance if you prefer.
A Peplink partner can provide part numbers and solution design advice. I would suggest you find a local one and start a discussion.
There are customers with 1000’s of devices managed using IC2, 500 is no problem.
Not convinced there is a limit - the IC2 team can confirm - but it would be many thousands.
You really need to find a local Peplink Partner to assist you. Where in the world are you based?