Please be sure that you have all necessary software components and hardware connections to properly connect your computer to the Internet.
You may want to first launch your web browser, visit www.ableton.com, and log-in, to be sure the connection works.
You can then reattempt the authorization, back in Ableton Live program → Live's Preferences → Licenses Maintenance → Authorize at ableton.com
Strong firewall settings may also cause the process to timeout, so please check that adequate settings are made in your operating system security center to allow authorization.
If you continue to experience issues, we would recommend an alternative web-browser to the one being used (for example, Firefox or Google Chrome) or to complete the offline authorization process.