I dont quite get the setting. It seems to be post apocalyptic but they have high-end gear? Is there anything I am missing here?
You're in the midst of a pandemic that began on Black Friday. It's determined that the virus was spread through bank notes and your job to get to the bottom of it. You're part of a classified agency called the Strategic Homeland Division. The SHD train their operatives to work with or without command, thus The Division.
In summation, the SHD are one of the last hopes to regain civility to the country.
The very very first teaser does explain that abit. This was the video before the gameplay came. Back in 2013.
https://www.youtube.com/watch?v=r1l2kEHsxa0