Kalite pi wireless AP configuration problems

Hi all,
We would like to setup a kalite raspberry as an offline wireless AP at schools here in South Africa.

We installed the debian OS and kalite 0.17 is running.
And we follow this Instructions to turn the PI into a wireless AP.
We are able to find the wireless network and connect to it but we can’t connect to the server on a client device.
Kalite status

Do you have any recommendations about on how to solve this?

Thanks in advance