Skill points are needed to buy new abilities and surprisingly you don't get them from leveling up. How to unlock Skill points in the Division 2 is achieved by progressing in the main story and completing the missions. You can hover over these missions on the map screen and they will tell you what they will unlock upon completion. Some offer settlement upgrades, some offer items, some offer Skill Points, or a combination of different rewards.
To ensure that you will unlock a Skill point you need to target the missions that have a yellow triangle on them as this indicates you are guaranteed to be rewarded a Skill point for successfully completing it. There will be instances where you will need to go through a mission that does not reward a Skill point in order to get to the mission that has one. Once you have completed all of the main missions you will have accumulated enough Skill points to get all of the skills in the game.
The quickest way to unlock Skill points is to focus on the main story missions for the game and complete them as fast as you can rather than participating in side activities.
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