The Phoenix Credits are the definite kind of game currency in The Division. They are the rarest kind of money and you can exchange them for some necessary gear, weapons, clothes, etc. with better characteristics. You need Phoenix Credits for buying the most powerful items. You can’t buy this currency for real money they must be earned.
At first you need to be 30 end game level to have the opportunity to gather the Phoenix Credits. You can get them few ways: to fulfill challenge modes or daily missions. 3 of them will appear on your map every day. You should do this to get from 15 to 20 Phoenix Credits. You must to play on hard. Win the Dark Zone bosses that can be met at the library, sports shop, etc. and you will have a chance to drop 1, 2 or 3 Phoenix Credits.
Besides that you are able to buy the Phoenix Credits at uPlay Store. There you can get the greatest amount of them – 60.
There are only 2 places where you will be able to exchange your Phoenix Credits for necessary items. The first one is located into safe house into the Dark Zone (the big church in the northern part of the map,). Here you can exchange your currency for yellow and purple items. And second vendor is upstairs at The Tech wing of your Base of Operations. You will find him on the left.