WARNING! This section of the wiki contains plot SPOILERS for the quests in Sim Settlements 2.
The Sim Settlements 2 Story is contained in the Main Quests. Currently, there are three chapters plus some additional content for PC only that is included in SS2 Extended.
You will meet Unique Characters during the main story quests and also, some Unique Settlers to recruit. Some will give you a Side Quest to complete before you can ask them to join one of your settlements.
If you encounter issues while questing:
Some Video Walkthroughs of Sim Settlement 2 quests are available.
Here are links to a few playlists: