I manage to connect wifi through Captive portal of ESP8266.
Now we need to connect to our customer wifi, They have firewall and safety inplace. therefor first we need to connect to the guest wifi then it opens the login page where we need to enter the seperate credentials and accept the policy by clicking on agree / ok button.
It means we first need to connect to guest wifi then need to enter user name and password on webpage then click ok to get though this.
Could not find proper solution, some guys talked about it over internet but no solution.