When trying to use open WiFi such as in a hotel or airplane and you have to go through an authorization page, you can have trouble getting started if your default page is something like https://google.com that is using HSTS headers and doesn't offer an HTTP option. Many times, the intermediate authorization page doesn't show up because the browser won't redirect from your HTTPS home page.
If this causes problems, you can always try to go first to http://neverssl.com which is HTTP only and will usually allow the intermediate authorization page to come up and get you started. Then, once online, you can proceed to setup a VPN connection, etc.