Story quest can be accessed from the Gwen icon just below your profile avatar (on the left side of the screen) or you can access it from game menu - Quest tab

Check ‘new’ tab often to see if you can start any new quests as you progress - some quests needs to be activated before you do some actions in the game, so make sure to activate them as soon as you see one available

Check ‘active’ tab to track which requirements you still need to work on to progress to next stage and collect rewards