My MacBook Pro is unable to connect to public WiFi

this message keeps popping up everytime i try to log onto wifi out in the public that has a terms agreement window. it will show that i am connected but i cannot access the internet whatsoever. anyone experience this before?

I was on the phone with apple support for over an hour last week and the guy was able to help me get it to work I. The hotel I was staying at but just tried again at the library and the message came back so obviously not a long term fix. Help. Here is a pic of the message that pops up.

[Re-Titled by Moderator]