While the VPN is not officially supported for Linux users, it does work in many distributions. You will need the 'network-manager' and 'ppp' packages for your distribution installed, then use the web-based login (vpn.brown.edu) - note that this currently doesn't work in all browsers (definitely not Chrome). You will also need superuser access to install the plugin.
Installing VPN Plugin (Pale Moon)
Install Pale Moon here: https://linux.palemoon.org/download/installer/
Sign in with your Brown credentials and your two-step authorization, if applicable.
Follow through on-screen prompts to install plugin; you may be asked to restart the browser.
Once plugin is installed, you will be able to connect through Brown VPN by going to this page.
See this installed on Ubuntu: