Installation

Install openconnect via pacman:

sudo pacman -S openconnect

Through Command Line

run 

sudo openconnect vpn.cites.illinois.edu

You should see a prompt that looks like 

GROUP: [1_SplitTunnel_Default|2_SplitTunnel_2FA_Duo|3_TunnelAll|4_TunnelAll_2FA_Duo|5_SplitTunnel_NoPrivate|6_SplitTunnel_NoPrivate_2FA]

Type in the option you wish to choose (typically 1_SplitTunnel_Default), hit enter. Note that it is possible to type the options partially, e.g., type 1 and immediately hit Enter will choose the  first option.

Enter netid and password as prompted, and that should connect you to university network.