Am having a access point and i want to connect up to 3000 client, please how do i configure the IP address that will accommodate these number of client.

I would assign the 192.168.0.1/24 to the first access point. That will handle about 50 well.
Then I would assign 192.168.1.1/24 to the second access point. That will handle about 50 well.
Then I would assign.....

I don't think there is an access point that will handle 3000 clients.

As much I know, maximum client that can be handle by access point is about 2007.